Conditionals
Conditionals are generally classified in three categories:
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The following are the verb forms used for the three categories:
Present/future - factual/predictive
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time |
if clause |
result clause |
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present (factual) |
simple present |
simple present |
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If I have time, I make bread every week. |
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future |
simple present |
future might + verb |
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If Jessica goes to the party, I'll go too. If I don't get a scholarship, I might get a job. |
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(uncertainty) |
should + verb |
present or future would + simple form |
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If my husband should call, tell him I am at lunch. If the President should decide to resign, many people would be happy. or ...will be happy. |
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Counterfactual (unreal) in the present
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time |
if clause |
result clause |
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present/future |
past subjunctive (BE = were)
were able to (could) |
would + verb could (would be able to) + verb might (would maybe) + verb |
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If I were a fish, I could breathe under water. If I could sing as well as you, I would (or might) join the opera. If I skied as well as you, I could be on the Olympic team. |
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Counterfactual (unreal) in the past
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time |
if clause |
result clause |
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past |
past perfect
past perfect progressive |
would have + past. part. could have + past. part. might have + past. part. would have been + pres. part. |
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If you had eaten breakfast, you wouldn't have fainted during the test. If you had been here earlier, you would have (could have; might have) seen the Queen. If I had been living in Chile last year, I would have been working at the bi-national center. |
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past/present |
past perfect |
would + verb |
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If I had done my homework last night, I would know the answers to the teacher's questions. |
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present/past |
past (BE => were) |
would have + past. part. |
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If he were a good student, he would have passed the conditional test. |
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Generally will is not used in if clauses, just as it is not used in adverb clauses expressing time relationships. However, there are a few exceptions.
If clauses (with will)
Will and won’t occur in adverbial clauses, particularly in if-clauses, in certain circumstances:
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Where the modals have a volitional (willingness) meaning: |
If you’ll help us, we can finish early. (are willing to) If you won’t help us, all our plans will be ruined. (refuse to)
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Where the modals express timeless and habitual prediction |
If drugs will cure him, this drug should do the job. If sugar will dissolve in a hot liquid, this chemical will do so too.
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Where the modals express the present predictability of the occurrence or nonoccurrence of a future event |
If you won’t arrive before six, I can’t meet you. (If you won’t be arriving before six) If the game won’t be finished until ten, I’ll spend the night at your place. (If the game is not going to be finished until ten) |
Unless in Conditional sentences
When the if clause expresses a negative condition, unless can be used to replace if + negative form of the auxiliary verb. There is no change in meaning.
If you don’t hurry, you’ll be late.
Unless you hurry, you’ll be late.