The “if” clause (also called a conditional clause) is a common structure in English sentences. An “if” clause indicates that if a certain condition is fulfilled, some other action will occur. If is sometimes paired with then. (If x, then y.) But even when then is not stated, the cause-effect relationship is understood.
- If you had listened to me, then you would have known what to do.
- If it keeps raining, we will postpone the game.
- If I had been there, I could have helped you.
Sentences with “if” clauses often include modal auxiliaries, such as would, could, or might, or subjunctive verbs.
- If I were (subjunctive) a movie star, I would (modal) live in Beverly Hills.
The tense of the verb in the “if” clause affects the tense of the verb in the clause that follows it. Common patterns are:
- “if” clause = simple present
- “then” clause = simple present
If you make a nice sauce for it, yak is delicious.
- “if” clause = simple present
- “then” clause = simple future
If you study, you will pass the exam.
- “if” clause = simple past
- “then” clause = modal auxiliary + base form
If a teacher discovered their cheating, they could be suspended.
- “if” clause = past perfect
- “then” clause = modal auxiliary + have + past participle
If Jill had been there, everything might have been different.
- “if” clause = subjunctive
- “then” clause = modal auxiliary + base form
If she were smart, she would start her research right now.
Sentences with “if” clauses can also issue commands.
- “if” clause = simple present
- “then” clause = imperative
- If you go to the store, buy an extra gallon of milk.