Conditional Sentences and Hypotheticals
~9 min read
- Four types: Zero (general truth), First (real future), Second (unreal present), Third (unreal past).
- If + tense rule: If-clause uses one tense lower than the main clause. Never use 'will' or 'would' in the if-clause (the 'if + would' error is the #1 CDS trap).
- Subjunctive: 'If I were you' (not 'was'), 'I wish I knew', 'It is high time he left' use subjunctive forms.
Conditional sentences appear in Spotting Errors and Sentence Improvement nearly every CDS paper. The wrong tense pairing across the if-clause and main clause is the most frequently planted error.
The Four Conditional Types
| Type | If-clause | Main clause | Use |
|---|---|---|---|
| Zero | If + present | present | General truths, scientific facts. If you heat ice, it melts. |
| First (Real future) | If + present | will + V1 | Likely future. If it rains, I will stay home. |
| Second (Unreal present) | If + past | would + V1 | Hypothetical present/future. If I were rich, I would travel. |
| Third (Unreal past) | If + past perfect | would have + V3 | Imagined past, regret. If I had studied, I would have passed. |
The Cardinal Rule
Never use 'will' or 'would' in the if-clause.
- Wrong: If you will work hard, you will succeed.
- Correct: If you work hard, you will succeed.
- Wrong: If I would have known, I would have come.
- Correct: If I had known, I would have come.
Exception: 'will' can appear in if-clause to mean 'be willing to': If you will please wait, I'll fetch him.
Mixed Conditionals
The condition is in one time, the result in another.
- Past condition → present result: If I had studied medicine, I would be a doctor now.
- Present condition → past result: If he were honest, he would have told the truth yesterday.
Subjunctive Forms
The subjunctive uses were for all persons in unreal/hypothetical contexts.
| Structure | Example |
|---|---|
| If I were... / If he were... | If I were you, I would resign. |
| I wish + past | I wish I knew the answer. (= I don't know) |
| I wish + past perfect | I wish I had attended the meeting. (= I didn't) |
| It is (high) time + past | It is high time we left. |
| As if / as though + past | He behaves as if he were the boss. |
| Suppose / supposing + past | Suppose he came tomorrow? |
| Mandative (demand, suggest, insist, propose) + that + bare verb | I insist that he be punished. |
Unless, Provided, In Case
| Connector | Meaning | Example |
|---|---|---|
| unless | if not | I'll go unless it rains. (= if it doesn't rain) |
| provided / provided that | only if | You may go provided you finish the work. |
| as long as | only if | I'll wait as long as you need. |
| in case | in the event that (precaution) | Carry an umbrella in case it rains. |
| but for + noun | if not for | But for your help, I would have failed. |
Common error: 'unless' already means 'if not', so don't double up.
- Wrong: Unless you don't hurry, you'll miss the bus.
- Correct: Unless you hurry, you'll miss the bus.
CDS/OTA PYQ Examples
Q: Improve: If I would have known about the meeting, I would have attended.
(a) If I knew (b) If I had known (c) If I would know (d) No improvement
Answer: (b) If I had known — Third Conditional: if + past perfect, main clause = would have + V3.
Q: Identify the error: If you will work / sincerely, you / will surely succeed. / No error
(a) If you will work (b) sincerely, you (c) will surely succeed (d) No error
Answer: (a) Never use 'will' in the if-clause. Correct: 'If you work sincerely'.
Q: Choose the correct option: If I ___ you, I would accept the offer.
(a) was (b) were (c) am (d) would be
Answer: (b) were — subjunctive 'were' for unreal/hypothetical present, even with singular subject.
Q: Improve: Unless you don't apologise, I won't speak to you.
(a) Unless you apologise (b) If you don't apologise (c) Until you apologise (d) Both (a) and (b)
Answer: (d) Both (a) and (b). 'Unless' already means 'if not'; never add 'don't' after it.
Q: Choose the correct option: It is high time we ___ for the airport.
(a) leave (b) left (c) had left (d) will leave
Answer: (b) left — 'It is high time' is followed by past subjunctive.
Q: Identify the error: I wish I / am able to / help you out. / No error
(a) I wish I (b) am able to (c) help you out (d) No error
Answer: (b) 'I wish' is followed by past tense for present unreal wishes: 'I wish I were able to' or 'I wish I could'.
Drill Conditional Sentences and Hypotheticals for CDS/OTA
CDS/OTA-pattern items on Conditional Sentences and Hypotheticals with answer keys and explanations.
Start Free Mock TestFrequently Asked Questions
Why 'If I were' and not 'If I was'?
The subjunctive 'were' marks the situation as unreal or contrary to fact. 'If I was' is grammatically tolerable in informal English but CDS scoring follows the prescriptive rule: use 'were' for hypothetical/contrary-to-fact statements with all subjects.
Can 'if' be replaced by 'had / were / should'?
Yes, in formal English, by inversion. 'Had I known' = If I had known. 'Were I you' = If I were you. 'Should you need help' = If you should need help. CDS sometimes tests this.
What's the difference between First and Second Conditional?
First Conditional describes a real, likely future ('If it rains, I will stay'). Second Conditional describes an imaginary or unlikely present/future ('If it rained tomorrow, I would stay' - suggests rain is less expected).
What is 'mandative subjunctive'?
After verbs of demand, suggestion, request, recommendation, insistence, the 'that' clause takes the bare infinitive: 'I suggest that he go.' 'The boss insisted that she be present.' CDS sometimes tests this.
Is 'but for' formal or colloquial?
Formal. 'But for your timely help, I would have failed' = 'If it had not been for your help...' Equivalent to 'were it not for' / 'had it not been for'. Frequently appears in CDS sentence-improvement options.