Conjunctions | Olive Defence

A conjunction is a word that joins two words, phrases or sentences. The most common errors tested in CDS/NDA/AFCAT are: using the wrong conjunction pair, mixing up although/but, and misusing since/for/ago. This module covers every pattern you need.

Section 1 — What is a Conjunction?

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The Basic Idea

Definition + 3 types at a glance

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A conjunction connects words, phrases or clauses. Without conjunctions, we would need many short, choppy sentences.

Simple Example

Without conjunction: She was tired. She kept studying.
With conjunction: She was tired but she kept studying.

There are three main types of conjunctions:

Type	What it does	Examples
Coordinating	Joins two equal parts (word+word, clause+clause)	for, and, nor, but, or, yet, so (FANBOYS)
Subordinating	Joins a main clause to a dependent clause	although, because, since, if, unless, until, when, while
Correlative	Come in pairs — one word at each junction	either…or, neither…nor, not only…but also, both…and

The Golden Rule

Correlative conjunctions must be placed immediately before the elements they connect. Whatever structure follows the first word of the pair must also follow the second word. This is called parallel structure — and it is the most tested conjunction rule in CDS/NDA.

Section 2 — Coordinating Conjunctions (FANBOYS)

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For, And, Nor, But, Or, Yet, So

The FANBOYS — and when to use each

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Conjunction	Meaning / Use	Example
For	Gives a reason (similar to "because" but more formal)	He rested, for he was exhausted.
And	Adds one thing to another	She cooked and he cleaned.
Nor	Adds a negative to a previous negative	He did not eat, nor did he sleep.
But	Shows contrast or exception	He tried hard but failed.
Or	Shows a choice or alternative	Study now or regret later.
Yet	Shows contrast (stronger than "but")	It was cold, yet they marched on.
So	Shows result or consequence	It rained, so we stayed inside.

⚑ Exam Trap — "For" vs "Because"

"For" as a conjunction always comes in the middle of a sentence (after a comma). It is never used at the beginning.
"Because" can start a sentence or come in the middle.
Correct: She left early, for she had a train to catch.
Wrong: For she had a train to catch, she left early.

Section 3 — Correlative Conjunctions (Most Tested)

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Either…or / Neither…nor

The most tested pair in CDS/NDA/AFCAT

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The Rule

Either…or → used for a positive choice between two things.
Neither…nor → used for a negative choice (both are not true).
Never mix them: "either…nor" and "neither…or" are always WRONG.

Correct Usage

Either you study or you fail.
Neither Ram nor Shyam was present.
Either the officer or the soldiers are responsible.

Common Errors

Either Ram nor Shyam came. → should be or
Neither he is honest or hardworking. → should be nor
Either of the two boys are good. → should be is (either = singular)

Subject-Verb Agreement with Either/Neither

When subjects are joined by either…or / neither…nor, the verb agrees with the nearer subject
Neither the students nor the teacher was present. (teacher = nearer, singular → was)
Neither the teacher nor the students were present. (students = nearer, plural → were)

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Not only…but also

Parallel structure is the key

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The Rule

The elements following "not only" and "but also" must be grammatically parallel — same type of word or phrase on both sides.

Correct (Parallel Structure)

He is not only brave but also intelligent. (adj + adj ✓)
She not only sings but also dances. (verb + verb ✓)
Not only the officer but also the soldiers were praised. (noun + noun ✓)

Wrong (Not Parallel)

He not only is brave but also with intelligence. ✗
She not only sings well but also a dancer. ✗

⚑ Exam Trap — "But" Without "Also"

Many students write "not only…but" without "also". While not always wrong in spoken English, in CDS/NDA exam questions the complete form "not only…but also" is always preferred and required.

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Both…and / Whether…or

Other important pairs

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Pair	Use	Example
Both…and	Includes two things (always positive, always plural verb)	Both Ram and Shyam are officers.
Whether…or	Presents two alternatives or expresses doubt	I don't know whether he passed or failed.
So…that	Shows result or consequence	He was so tired that he fell asleep.
Such…that	Used with nouns (such + noun + that)	It was such a hot day that we stayed inside.
No sooner…than	One thing happens immediately after another	No sooner did he arrive than it rained.
Hardly/Scarcely…when	Same as "no sooner" — simultaneous events	Hardly had he sat down when the bell rang.

⚑ Critical Traps

Both…and always takes a plural verb: "Both Ram and Shyam are present" (never "is")
No sooner…than — never use "when" after "no sooner": No sooner did he leave when it rained ✗ → must be than
Hardly/Scarcely…when — never use "than" after hardly/scarcely: must be when/before

Section 4 — Subordinating Conjunctions

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Although / Though / Even though / Despite / In spite of

Contrast conjunctions — most confused group

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These all show contrast — "unexpected result." But they work differently grammatically.

Word	Followed by	Example
Although / Though / Even though	Subject + Verb (full clause)	Although he was tired, he kept going.
Despite / In spite of	Noun / Noun phrase / Gerund (-ing)	Despite his fatigue, he kept going.

Classic Exam Errors

Although his hard work, he failed. ✗ → Despite his hard work, he failed. ✓
Despite he was tired, he worked. ✗ → Although he was tired, he worked. ✓
Although he worked hard, but he failed. ✗ → Never use "but" after "although"
In spite of he tried hard, he failed. ✗ → In spite of his hard work, he failed. ✓

⚑ The Biggest Trap — "Although…but"

This is the most common error in CDS English. "Although" and "but" both show contrast — you cannot use both in the same sentence. Use one or the other, never both.

Although he was rich, but he was unhappy. ✗
Although he was rich, he was unhappy. ✓
He was rich, but he was unhappy. ✓

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Since / For / Ago

Time conjunctions — endlessly tested

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Word	Used with Tense	Refers to	Example
Since	Perfect tense (has/have/had)	A point in time	He has been here since Monday.
For	Perfect tense (has/have/had)	A period/duration	He has been here for three days.
Ago	Simple past only	Time before now	He came here three days ago.

Common Errors

He is working here since five years. ✗ → for five years ✓
He has joined the army three years ago. ✗ → He joined the army three years ago ✓
He came here since Monday. ✗ → He has been here since Monday ✓

Memory Trick

Since = a specific starting point (since 2019, since morning, since Monday)
For = a span of time (for 3 years, for two hours, for a long time)
Ago = looks backward from now — always simple past, always at the END

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Unless / Until / If

Conditional conjunctions

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Word	Meaning	Example
If	A condition (may or may not happen)	If you study, you will pass.
Unless	"If not" — negative condition	Unless you study, you will fail.
Until / Till	Up to a point in time	Wait here until I return.

⚑ Critical Traps

Unless already means "if not" — never add "not" again: Unless you do not study… ✗ → Unless you study… ✓
After if / unless / until / when — use present tense, never future: If it will rain… ✗ → If it rains… ✓
Until = time · Unless = condition. Don't mix them.

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Because / As / Since / So that

Cause and effect conjunctions

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Word	Shows	Example
Because	Direct reason (strongest cause)	He failed because he didn't study.
As / Since	Reason (milder, often already known)	As it was raining, we stayed inside.
So that / In order that	Purpose / intention	He ran fast so that he could catch the bus.
Therefore / Hence / Thus	Conclusion / result (not conjunctions — they are conjunctive adverbs)	He was ill; therefore he rested.

⚑ Exam Trap — "Because of" vs "Because"

Because → followed by subject + verb (clause): He left because he was ill.
Because of → followed by noun/noun phrase: He left because of his illness.
He left because of he was ill. ✗ (because of + clause is always wrong)
He left because his illness. ✗ (because + noun alone is wrong)

Section 5 — Commonly Confused Pairs

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While / When / As

Time clauses — often mixed up

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Word	Used when…	Example
While	Two long/continuous actions happening at the same time	While I was reading, she was cooking.
When	A short action happens at a point in time / during another	When he arrived, I was sleeping.
As	Two short actions happening simultaneously	As he entered, everyone stood up.

Errors to Avoid

While he entered, everyone clapped. ✗ → As/When he entered… ✓ ("entered" is instantaneous, not continuous)
When I was studying, she was singing. ✗ → While I was studying… ✓ (two ongoing actions)

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Lest / So that / In order that

Purpose conjunctions — formal English tested in CDS

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The Rule for "Lest"

Lest means "for fear that" or "in case." It is always followed by "should" — never by "not" (it already has a negative meaning built in).

Correct Usage of Lest

Walk carefully lest you should fall. ✓
Study hard lest you should fail. ✓

Common Errors with Lest

Walk carefully lest you should not fall. ✗ (never use "not" with lest)
Walk carefully lest you will fall. ✗ (never use will/would)
Walk carefully lest you fall. ✗ (must use "should")

Section 6 — Top 6 Exam Traps Summary

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All Major Traps at a Glance

Review before the exam

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⚑ 6 Rules That Appear Every Year

Although…but — never together. Use one. Although he was tired, but he worked. ✗
Either…or / Neither…nor — never mix. Either…nor ✗ · Neither…or ✗
Unless already means "if not" — don't add "not": Unless you don't study… ✗
No sooner…than (not "when"): No sooner did he arrive when… ✗
Lest…should — no "not", no "will": Lest he should not fall ✗
Since/For/Ago — "ago" only with simple past; "since/for" with perfect tenses

Use this for last-minute revision. Scan the key rules and correct/wrong pairs before your exam.

FANBOYS — Coordinating

For = reason (never starts a sentence)
And = addition
Nor = negative addition (after negative)
But = contrast
Or = choice/alternative
Yet = strong contrast
So = result/consequence

Correlative Pairs

Either…or · Neither…nor
Not only…but also
Both…and → always plural verb
Whether…or
No sooner…than (never "when")
Hardly/Scarcely…when (never "than")
So…that · Such…that

Contrast Conjunctions

Although/Though/Even though + clause
Despite/In spite of + noun/gerund
Although…but = WRONG always
Despite + clause = WRONG always
Although + noun = WRONG always
However = conjunctive adverb (needs semicolon or new sentence)

Since / For / Ago

Since = specific point (since 2010, since Monday)
For = duration (for 3 years, for ages)
Ago = past tense only, at end of phrase
Has been here since five years = WRONG
Has joined ago = WRONG
Since/For → always perfect tense

Conditional Conjunctions

Unless = if not (never add "not")
Until/Till = time · Unless = condition
After if/unless/when/until → present tense
If it will rain = WRONG
Unless you don't come = WRONG
Lest…should — no "not", no "will"

Because / Because of

Because + subject + verb (clause)
Because of + noun/noun phrase
Because of he was ill = WRONG
Because his illness = WRONG
As/Since = mild reason (known fact)
So that/In order that = purpose

While / When / As

While = two long/continuous actions together
When = short action at a point in time
As = two simultaneous short actions
While he entered = WRONG (use "as/when")
When I was studying, she singing = WRONG

Attempted

Correct

Wrong

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0 of 25 answered

Conjunctions &Connectors

Conjunctions &
Connectors