@HydRocker said:

Many a man were here. (incorrect)Many a man was here. (correct)My state of health. (incorrect)The state of my health. (correct)I don't know the English alphabets. (incorrect)I don't know the English alphabet. (correct)

@HydRocker said:

May I take your leave. (incorrect)May i take leave of you. (correct)

@HydRocker said:

Excuse me being late. (incorrect)Excuse my being late. (correct)He rarely goes out, doesn't he? (incorrect)He rarely goes out, does he? (correct)He admitted that he was in wrong. (incorrect)He admitted that he was in the wrong. (correct)The number of people are small. (incorrect)The number of people is small. (correct)My litter sister goes to the school by bus. (incorrect)My little sister goes to school by bus. (correct)The series of lectures were boring. (incorrect)The series of lectures was boring. (correct)He lives in a boarding. (incorrect)He lives in a boarding room. (correct)You are wiser than old. (incorrect)You are more wise than old. (correct)A good play of football. (incorrect)A good game of football. (correct)He behaves as if he was a king. (incorrect) He behaves as if he were a king. (correct)They were counting on me helping them. (incorrect)They were counting on my helping them. (correct)This drawing is more perfect than the other one. (incorrect)This drawing is perfect than the other one. (correct)

@HydRocker said:

Word by word translation is not necessary. (incorrect)Word for word translation is not necessary. (correct)Two third of the book. (incorrect)Two thirds of the book. (correct)No space in this compartment. (incorrect)No room in this compartment. (correct)Put pen on paper. (incorrect)Put pen to paper. (correct)

@pravinfiat said:

hat's off sir.............. Its been helpful during my last days of CAT preparation.Thank you so much for your guidance.Do you have english literature PHD ?

@HydRocker said:

@HydRocker . thanks anna manchi info post chesinav

@shubhamtyl said:

identfy the incorrect sentences.

a. The road is under repair. b. Vehicles are diverted into other roads. c. Two-third of the work is completed. d. The road will open for traffic next week.

a, b and d

b, c and d

a and d

a and c

B,C,D are incorrect

My explanations:

Hi Estallar Regarding 3 yeah you are right. But in the solution with me. Correct ans is option D a&c;

@shubhamtyl said:

identfy the incorrect sentences.

a. The road is under repair. b. Vehicles are diverted into other roads. c. Two-third of the work is completed. d. The road will open for traffic next week.

a, b and d

b, c and d

a and d

a and c

Nopes !! Please answer with explainations

a. The road is under repair.
b. Vehicles are

diverted into other roads.
c. Two-third of the work is completed.
d. The road will open for traffic next week.

answer is option a : a, b, d

a. The road is under repair.
b. Vehicles are diverted into other roads.
c. Two-third of the work is completed.
d. The road will open for traffic next week.

@avik.ch said:

This is a case of hypothetical subjunctive : this type of construction is generally to indicate unlikely or unreal condition. marker word : if...then, as...if, as though...

consider this :

to overcome my fear of pain, i will think about disease as if it were harmless.

if i were rich, i would have....

hope this helps !!

@saurav5517 said: puys...wats the basic difference between the english of CAT and GMAT ??

is it true CAT uses more of day to day english whereas GMAT more of business type of english..

For an example is the following sentence grammatically correct?

A waiter was serving drinks in a blue dress..

As regards me i think serving is the modifier here and as no comma is here it modifies the preceeding noun waiter and thereby the sentence is correct ..

PHONE:

@sonamaries7 said:

were is ok?...can u plz share the complete rule?..

@spectramind07 said:

There are multiple errors in some of them!!!!

@guravus said: Can someone please help me with the errors in the following statements and the reasons.

1. A knowledge/ of Sanskrit/ may be helpful/ to chant slokas.

2. The new tapes/ highlight C TV's/ Barkha Verma's clout/ with the Congress party.

3.The new teacher/ told the principal that/ the behavior of the class/ were highly objectionable.

4. The members of the committee/ felt that they needed/ another information before/ they could arrive at a decision.

5. However much you may/ try to dress it with/ perks and incentives/ office work is not glamorous.

6. While in Madrid/ I took the subway/ although I have been told/ that it was dangerous.

7.Globalization today has passed/ the point of no return/ we can't pause it/ we can't reverse it.

Kindly post if you find multiple ways to correct it...will post the OA in a while

@saurav5517 said: puys...wats the basic difference between the english of CAT and GMAT ??

is it true CAT uses more of day to day english whereas GMAT more of business type of english..

For an example is the following sentence grammatically correct?

A waiter was serving drinks in a blue dress..

As regards me i think serving is the modifier here and as no comma is here it modifies the preceeding noun waiter and thereby the sentence is correct ..

Can someone please help me with the errors in the following statements and the reasons.

purwar_ankit
she is used in subjective case whereas her is use in objective case

can someone explain use of 'she/her'

ADVERBS: How adverbs are formed

Rules

1. In most cases, an adverb is formed by adding '-ly' to an adjective:
Adjective Adverb

cheap cheaply
quick quickly
slow slowly

Examples:

* Time goes quickly.
* He walked slowly to the door.
* She certainly had an interesting life.
* He carefully picked up the sleeping child.


Rules

If the adjective ends in '-y', replace the 'y' with 'i' and add '-ly':
Adjective Adverb

easy easily
angry angrily
happy happily
lucky luckily

If the adjective ends in -'able', '-ible', or '-le', replace the '-e' with '-y':
Adjective Adverb

probable probably
terrible terribly
gentle gently

If the adjective ends in '-ic', add '-ally':
Adjective Adverb

basic basically
economic economically
tragic tragically

Note: Exception: public - publicly

2. Some adverbs have the same form as the adjective:
Adjective and Adverb

early late
fast near
hard straight
high wrong

Compare:

* It is a fast car.
* He drives very fast.
* This is a hard exercise.
* He works hard.
* We saw many high buildings.
* The bird flew high in the sky.

3. 'Well' and 'good'

'Well' is the adverb that corresponds to the adjective 'good'.

Examples:

* He is a good student.
* He studies well.
* She is a good pianist.
* She plays the piano well.
* They are good swimmers.
* They swim well.

ADVERBS - FUNCTION

Adverbs modify, or tell us more about other words, usually verbs:

Examples

* The bus moved slowly.
* The bears ate greedily.

Sometimes they tell us more about adjectives:

Examples

* You look absolutely fabulous!

They can also modify other adverbs:

Examples

* She played the violin extremely well.
* You're speaking too quietly.

puys...wats the basic difference between the english of CAT and GMAT ??

@anudsweet said: please tell if both sentences are correct in terms of usage: The condition of a country's athletes/ has worsened.

please tell if both sentences are correct in terms of usage:
The condition of a country's athletes/ has worsened.

@avik.ch said:

i am not sure what you are asking...

if your doubt is whether - "If I Were....- plural "were" is correct, then its perfectly fine to signify hypothetical scenario.

Hope this helps !!

@sonamaries7 said: he looks as if he "were" weary...is this correct usage?..is this followed in CAT also..this form is used in American Englisg...puys any idea? plz quote the rule used(with links/refernces)

he looks as if he "were" weary...is this correct usage?..is this followed in CAT also..this form is used in American Englisg...puys any idea?
plz quote the rule used(with links/refernces)

@sonamaries7 said: puys, plz help me with the foll statements: PIck a suitable fill: 1) Good students like you and he/him should study regularly. 2)what can we do to stop them/their worrying about us.PS: plz provide the logic alsoThanks

I posted an explanation here : http://www.pagalguy.com/forums/verbal-ability/sentence-correction-cat-2012-t-74732/p-3051705?page=77

Hope this helps !!

puys, plz help me with the foll statements:
PIck a suitable fill:
1) Good students like you and he/him should study regularly.
2)what can we do to stop them/their worrying about us.

PS: plz provide the logic also

Thanks

@srustijit said: This is the girl that failed in the exam. Can we also write it as: This is the girl who failed in the exam.Also please tell the cases where we need to use "that" instead of "which".

@Mad-Head said: If you have Wren & Martin & find it Old & Outdated then not sure what to suggest you! Its 1 of the best Grammar Book in India & UK. My Dear friend, Grammar is not like a cricket score that changes every minute. Over years only couple of things changes in grammar. So, if you are saying that Wren n Martin is OLD then I'm not sure what do you mean by that??? If you still want to go for another book apart from Wren n Martin then go for Oxford Guide to English Grammar by John Eastwood/Longman's grammar of spoken an written english. You can also check below website link for online learning: www.grammarbook.com/

A@jeetuachtani said: Hi everyonem looking best resource for grammari do have wren n martin..but..its quite old thing for now...ANY WEBSITE may be..the best one.will doWAITING FOR UR RESPONSE>>pls help me weak in dat

Hi everyone

m looking best resource for grammar

i do have wren n martin..but..its quite old thing for now...ANY WEBSITE may be..the best one.will do

WAITING FOR UR RESPONSE>>pls help me weak in dat

COMPARISON OF ADJECTIVES II:

THE + SUPERLATIVE


Rule:

'the' is placed before the superlative:


Examples:

* He is the richest man in the world.
* That is the biggest crocodile I have ever seen.
* She is the tallest girl in her class.

COMPARATIVE + THAN

To compare the difference between two people, things or events.


Examples

* Mt. Everest is higher than Mt. Blanc.
* Thailand is sunnier than Norway.
* A car is more expensive than a bicycle.
* Albert is more intelligent than Arthur.


AS + ADJECTIVE + AS

Usage

To compare people, places, events or things, when there is no difference, use as + adjective + as:


Examples

* Peter is 24 years old. John is 24 years old. Peter is as old as John.
* Moscow is as cold as St. Petersburg in the winter.
* Ramona is as happy as Raphael.
* Einstein is as famous as Darwin.
* A tiger is as dangerous as a lion.

@[521882:Preeti_L] Thank u so much... will refer those books..

@[589515:matangi.prasan]
In case u feel u r weak in English, start with basics. CAT is more of basics.
Read good stuff where you can read n analyse so that u may put in ur basics learnt there. As you proceed, put the basics into usage.
For VA n stuff, u may refer Barron's GRE.. That ample for wordlists.
Guess, VA by Arun Sharma is exhuastive, u refer n start ur prep.
ATB !

difference bw its and it's

it's is used for contraction

its is used as possession

however for nouns 's is the case for both possession and contraction,

COMPARISON OF ADJECTIVES:

FORMING THE COMPARATIVE AND SUPERLATIVE

Using the comparative of adjectives in English is quite easy once you have understood the few simple rules that govern them.

Below you will find the rules with examples for each condition.

If you are not sure what a syllable or a consonant is - have a look here.
Rules
Number of syllables Comparative Superlative (see rule)
one syllable + -er + -est

tall taller tallest



one syllable with the spelling consonant + single vowel + consonant: double the final consonant:

fat fatter fattest

big bigger biggest

sad sadder saddest




Number of syllables Comparative Superlative
two syllables + -er OR more + adj + -est OR most + adj


ending in: -y, -ly, -ow
ending in: -le, -er or -ure
these common adjectives - handsome, polite, pleasant, common, quiet
happy happier/ more happy happiest/ most happy

yellow yellower/ more yellow yellowest/ most yellow

simple simpler/ more simple simplest/ most simple

tender tenderer/ more tender tenderest/ most tender


If you are not sure, use MORE + OR MOST +
Note: Adjectives ending in '-y' like happy, pretty, busy, sunny, lucky etc:. replace the -y with -ier or -iest in the comparative and superlative form

busy busier busiest



Number of syllables Comparative Superlative
three syllables or more more + adj most + adj
important more important most important

expensive more expensive most expensive
Examples

* A cat is fast, a tiger is faster but a cheetah is the fastest
* A car is heavy, a truck is heavier, but a train is the heaviest
* A park bench is comfortable, a restaurant chair is more comfortable, but a sofa is the most comfortable

Puys,

Please suggest some material for english... Mainly english usage and VA... Do I need to do a whole book of grammar starting from basics or is it advisable to just practice more considering the time constraint....which material shld i refer for practice.... My grammar is pretty weaaaakkkkkkk... PLsssssssssssssssssssss

hie puyzz...today i came across a question which i really think is worth asking.

ques) the soldiers were tired .They ______ out the blanket ....

options--> (1)should have taken
(2) should take

this was the question asked in gate exam..the answer has been officially declared as opt (2) according to iit delhi...kindly reply as I am unable to figure out how?

RULES FOR USE OF PRONOUNS :-

16) Uses of WHICH :-
Which is used in the following ways:
1) For infants, small animals, and objects.
Eg:- This is the baby which was lost in the theatre.
This is the dog which my friend brought from the kennel's club.
2) When selection is expressed.
Eg:- Which of these television sets do you want to purchase?
3) To refer to a sentence.
Eg:- He was said to be drunk, which was not true.


17) Uses of THAT :-
That is used in the following ways :
1) For persons, lifeless things and small animals in the singular or in the plural number.
Eg:- This is the girl that failed in the exam.
This is the radio that i brought yesterday.
2) As a substitute for a singular noun already mentioned.
Eg:- The weather of Hyderabad is far better than Chennai. ( Wrong )
The weather of Hyderabad is far better than that of chennai ( Correct )
3) After a noun phrase used as direct object.
Eg:- I vividly remember the night that she came.

This is the girl that failed in the exam.
Can we also write it as: This is the girl who failed in the exam.


Also please tell the cases where we need to use "that" instead of "which".

FORM AND FUNCTION OF ADJECTIVES III:

Order of Adjectives:

Rules

Where a number of adjectives are used together, the order depends on the function of the adjective. The usual order is:

Value/opinion, Size, Age/Temperature, Shape, Colour,
Origin, Material

Value/opinion delicious, lovely, charming
Size small, huge, tiny
Age/Temperature old, hot, young
Shape round, square, rectangular
Colour red, blonde, black
Origin Swedish, Victorian, Chinese
Material plastic, wooden, silver


Examples:

* a lovely old red post-box
* some small round plastic tables
* some charming small silver ornaments

Q1) He was sent to ____ prison for fourteen years.

1) a
2) an
3) the
4) No article is required.

Q2) On Sundays, he stayed in ____ bed till noon.

1) a
2) an
3) the
4) No article is required.

Please reply with explanation.

Hi Ankit,

Kindly post all Fill in the Blanks on this thread:
http://www.pagalguy.com/forum/english-resources/74727-fill-in-blanks-cat-2012-a.html
As far as answer is concerned to your above post, for both no article is needed as prison & bed is not specified. If yu would be talking about a specific prison like Tihar Jail & bed (in the room) then article "THE" would have been used.

Q1) He was sent to ____ prison for fourteen years.

1) a
2) an
3) the
4) No article is required.

Q2) On Sundays, he stayed in ____ bed till noon.

1) a
2) an
3) the
4) No article is required.

Please reply with explanation.

FORM AND FUNCTION OF ADJECTIVES II:

Function of Adjectives

Adjectives can:

Describe feelings or qualities:

Examples

* He is a lonely man
* They are honest people

Give nationality or origin:

Examples

* Pierre is French
* This clock is German
* Our house is Victorian

Tell more about a thing's characteristics:

Examples

* A wooden table.
* The knife is sharp.

Tell us about age:

Examples

* He's young man
* My coat is very old

Tell us about size and measurement:

Examples

* John tall man.
* This is a very long film.

Tell us about colour:

Examples

* Paul wore a red shirt.
* The sunset was crimson and gold.

Tell us about material/what something is made of:

Examples

* It was a wooden table
* She wore a cotton dress

Tell us about shape:

Examples

* A rectangular box
* A square envelope

Express a judgement or a value:

Examples

* A fantastic film
* Grammar is boring.

FORM AND FUNCTION OF ADJECTIVES:
Rules:

1. Adjectives are invariable:
They do not change their form depending on the gender or number of the noun.

a) A hot potato
b) Some hot potatoes

2. To emphasise or strengthen the meaning of an adjective use 'very' or 'really':

a) A very hot potato
b) Some really hot potatoes.

Position of adjectives

a) Usually in front of a noun: A beautiful girl.

b) After verbs like "to be", "to seem" , "to look", "to taste":
Examples

* The girl is beautiful
* You look tired
* This meat tastes funny.

c) After the noun: in some fixed expressions:
Examples

* The Princess Royal
* The President elect
* a court martial

d) After the noun with the adjectives involved, present, concerned:
Examples

1. I want to see the people involved/concerned (= the people who have something to do with the matter)
2. Here is a list of the people present (= the people who were in the building or at the meeting)

Be careful! When these adjectives are used before the noun they have a different meaning:

* An involved discussion = detailed, complex
* A concerned father = worried, anxious
* The present situation = current, happening now

English Punctuation VI:

Hyphens and Dashes (-):

A hyphen joins two or more words together (e.g. x-ray, door-to-door) while a dash separates words into parenthetical statements (e.g. She was trapped - no escape was possible.

Hyphens:

Generally, hyphens are used to avoid confusion or ambiguity but today most words that have been hyphenated quite quickly drop the hyphen and become a single word (e.g. e-mail and email, now-a-days and nowadays). In many cases though a hyphen does make the sense clear:

* I am thinking of re-covering my sofa (to put a new cover on it)
* I would like to recover my sofa. (perhaps from someone who has borrowed it as this means 'to get it back')

Hyphens and numbers

1. Use a hyphen with compound numbers from twenty-one to ninety-nine.

* fifty-one
* eighty-nine
* thirty-two
* sixty-five
* eighty-one

2. In written fractions place a hyphen between the numerator and denominator.

* two-fifths
* one-third
* three-tenth
* nine-hundredth

if there is already a hyphen in either the numerator or the denominator, you omit the hyphen between the numerator and denominator.

* sixty-nine eighty-ninths (not 'sixty-nine-eighty-ninths')
* twenty-two thirty-thirds

3. Use a hyphen when the number forms part of an adjectival compund:

* France has a 35-hour working week.
* He won the 100-metre sprint.
* Charles ****ens was a great nineteenth-century novelist.

Check for Parallelism

Two or more words, phrases, or clauses that are similar in length and grammatical form. Also called parallelism. By convention, items in a series appear in parallel grammatical form: a noun is listed with other nouns, an -ing form with other ing forms, and so on. Failure to express such items in similar grammatical form is called faulty parallelism.

Just as the expressions on each side of an algebraic equation must be equivalent, so too must the parts of speech on either side of a conjunction be the same. By thinking about a conjunction in a sentence as an equal sign, you can identify and correct this error.

We will directly jump to examples to see what it says.

IC: Formerly, science was taught by the textbook method, while now the laboratory method is employed.
C: Formerly, science was taught by the textbook method; now it is taught by the laboratory method.

IC: The French, the Italians, Spanish, and Portuguese
C: The French, the Italians, the Spanish, and the Portuguese

IC: In spring, summer, or in winter
C: In spring, summer, or winter (In spring, in summer, or in winter)

IC: It was both a long ceremony and very tedious.
C: The ceremony was both long and tedious.

IC: Either you must grant his request or incur his ill will.
C: You must either grant his request or incur his ill will.

Parallelism is especially important in displayed enumerations:
POOR: This article will discuss:
1.How to deal with corporate politics.
2.Coping with stressful situations.
3.What the role of the manager should be in the community.

BETTER: This article will discuss:
1.Ways to deal with corporate politics.
2.Techniques of coping with stressful situations.
3.The role of the manager in the community.

References:
Parallel Form
parallel structure - definition and examples of parallel structures

English Punctuation V:

Apostrophe ('):

The apostrophe probaly causes more grief than any of the other punctuation marks put together!

The problem nearly always seems to stem from users not understanding that the apostrophe has two very different (and very important) uses in English.
# to show possession and ownership - e.g. Jack's car. Mary's father.
# to indicate a contraction - he's (he is), we're (we are), they're (they are)

The POSSESSIVE APOSTROPHE

In most cases you simply need to add 's to a noun to show possession:

* a ship's captain, a doctor's patient, a car's engine, Ibrahim's coat, Mirianna's book.

Plural nouns that do not end in s also follow this rule:

* the children's room, the men's work, the women's club

Ordinary (or common) nouns that end in s, both singular and plural, show possession simply by adding an ' after the s but proper nouns (names of people, cities, countries etc.) can form the possessive either by adding the 's or simply adding the ':

* a. The Hughes' home (or the Hughes's home), Mr Jones's shop (or Mr Jones' shop), Charles' book (or Charles's book)
* b. the ladies' tennis club, the teachers' journal, the priests' church (note that the priest's church would only be refering to one priest while the priests' church refers to a group.)

The APOSTROPHE for CONTRACTION

The most common use of contracted apostrophes is for:

* has'nt = had not
* can't = can not
* there's = there is
* mustn't = must not
* I'm = I am
* it's = it is
* let's = let us
* I've = I have (also they've, we've)
* she's = she has or she is (also he's)

English Punctuation IV:

Brackets and Parentheses () :

The difference between a 'bracket' and a 'parentheses' can be a bit confusing.

Generally, parentheses refers to round brackets () and brackets to square brackets []. However, we are more and more used to hearing these refered to simply as 'round brackets' or 'square brackets'.

Usually we use square brackets - [ ] - for special purposes such as in technical manuals. Round brackets - ( ) -, or 'parentheses' are used in a similar way to commas when we want to add further explanation, an afterthought, or comment that is to do with our main line of thought but distinct from it.

For example:

# further explanation - The government's education report (April 2005) shows that the level of literacy is rising in nearly all areas.
# comment - I visited Kathmandu (which was full of tourists) on my way to the Himalayas for a trekking expedition.


The Semi Colon (;):

The semicolon is somewhere between a weak full stop and a strong comma and used to join phrases and sentences without having to use a conjunction (and, but etc.) where the phrases or sentences are thematically linked but independent.

For Example:

Many great leaders; Churchill, leader of Britain during the Second World War; Alexander, the great Roman Emperor and general; and Napolean, the brilliant French general, had great strengths of character which were useful when their countries were at war but also great weaknesses which did not serve them so well in times of peace.


The Colon (:)

Always remember = The colon expands on the sentence that precedes it.

For Example:

* There are many reasons for poor written communication: lack of planning, poor grammar, misuse of punctuation marks and insufficient vocabulary.
* He collected a strange assortment of items: bird's eggs, stamps, bottle tops, string and buttons.
* Peter had an eclectic taste in music: latin, jazz, country and western, pop, blues and classical.

The boss suggested (that) we leave
early.
The boss suggested (that) we should
leave early.
All these forms are possible with little
or no difference in nuance, although
the subjunctive form, suggested we
leave, is a touch more formal.
suggest / insist / demand /
recommend
Suggest is one of those verbs of
advice that cannot be followed by the
more usual pattern of object +
infinitive but has to be followed by a
that-clause with should + infinitive
or with past, present or subjunctive
form verbs.
Insist, demand and recommend
(among others) also follow this
pattern, but other verbs that suggest
that something is desirable or
necessary or important follow the
object + infinitive pattern. Compare
the following:
I asked him / told him to stop phoning
me.
I implored him / begged him to stop
phoning me.
I insisted / demanded that he
should stop phoning me.
I insisted / demanded that he
stopped phoning me.
I insisted / demanded that he stop
phoning me.
Everyone urged her to continue with
her education for a further three
years.
Everyone advised her to continue
with her education for a further three
years.
Everybody recommended that she
should continue with her education
for 3 more years.
Everybody recommended that she
continued with her education for 3
more years.
Everybody recommended that she
continue with her education for 3
more years.
Even her granny recommends that
she continues with her education for
3 more years.
important / desirable / essential /
vital / imperative
These adjectives, when they are used
to express similar ideas, are also
followed by a that-clause with should
+ infinitive or with present, past or
subjunctive form verbs:
It is vitally important (that) you
should take this medication night and
morning.
It is vitally important (that) you take
this medication night and morning
without fail.
It was desirable (that) she should
go to a school where Italian was
taught.
It was desirable (that) she go to a
school where Italian was taught.
It was desirable (that) she went to a
school where Italian was taught.
In examples like these, you can avoid
a that-clause , if you wish to, by using
a for + object + infinitive
construction, which sounds slightly
less formal:
It is important for you to take this
medicine twice a day.
It was considered desirable for her to
attend a school where Italian was
taught.
the subjunctive
The subjunctive is a special kind of
present tense which has no -s in the
third person singular and where the
same forms are used in both present
and past situations when we want to
sound slightly formal. The verb to be
has a special subjunctive form, see
below:
The school governors insisted that he
resign from his post as deputy head
immediately.
They suggested that Mrs Giddy be
appointed as deputy head on a
temporary basis:
"We propose that Mrs Giddy be
appointed as deputy head until the
end of the school year. It is of vital
importance that she be present at the
interviews when other teachers are
selected."
The doctors recommended that my
father remain in hospital for a further
five days and that he return to work
only when fully fit.
Note that do is not used in negative
subjunctive sentences:
They advised that he not return to
work until fully fit.

Ambiguity of pronouns

This topic is rather shorter and easy to understand as compared to previous ones.

Pronouns replace nouns examples include he, she, them, we, mine and they. They help make sentences less repetitive. But when you create sentences, the reader must be able to identify what noun the pronoun is referring to, or else it will be confusing/ambiguous to the reader.
For example, you see a vacuum cleaner ad on TV. Their slogan is:

Dont kill your wife with work. Do it with electricity!

What is it? Is it the work that should be done with electricity, or it killing your wife? This ad didnt intend to say that you should kill your wife with electricity, but neither it is clear that it didnt mean so.

Here are some ways to avoid ambiguous pronouns:
check backwards through the sentence until you come across the noun that is being referred to
ensure that you have the correct pronoun gender (he, she)
ensure you have the right number (singular or plural)

1.What are you talking about?

Which noun is the pronoun referring to? The possible answers may try to trick you into using the incorrect noun to judge the pronoun.
It is believed that the suicide bomber drove a car laden with explosives next to the bus before detonating it.

Before detonating it what is it? Is it the car? Is it the bus? Neither. It is actually the explosives. But explosives is plural, so it must be replaced with them:
It is believed that the suicide bomber drove a car laden with explosives next to the bus before detonating them.
The above sentence is grammatically correct. And since explosives is the only plural noun in the sentence, it makes the meaning clear that them refers to the explosives and nothing else.

2.Who are you talking about?

Consider this sentence:
The virus that causes the common cold is always evolving, and it is doubtful whether they will ever be able to find a reliable drug to combat it.
Who does they refer to? This pronoun is pretty vague they could be any sorts of people clowns, hockey players, bookkeepers. For this sentence to sound credible and less clumsy a wise answer choice would probably look like this:

The virus that causes the common cold is always evolving, and it is doubtful whether scientists will ever be able to find a reliable drug to combat it.
Here we have simply replaced they with scientists. Now we know who we are talking about!

References:
Sentence correction: ambiguous pronouns - GMAT 2012

My Take:

b>export of
c>Aircraft

Ques: Identify the incorrect sentence
A) Mr. Medvedev's decree
B) prohibited exports
C) of tanks, aircrafts
D) and sea vessels to Iran.

my take:
Option B

plural following plural.... so it should be prohibited export of