First conditional/Zero conditional

First conditional

Look at the first conditional. Notice the different clauses.

if clause	main clause
( if + Present Simple)	(will/won't + infinitive)
If I start teaching again,	I'll be exhausted after a year

·    The first conditional talks about the result of a possible event or situation in the future.

·    The if clause talks about things that are possible, but not certain: If I start teaching again, I'll be exhausted after a year (maybe I will start teaching again).

   The main clause says that we think the result will be in this situation (I'm sure I will be exhausted after a year).

·    We make the first conditional with: if+ Present Simple, will/won't + infinitive

·    The if clause can be first or second in the sentence: I'll be exhausted after a year if I start teaching again.

·    We often use might in the main clause to mean ' will perhaps': But you might have to wait until next year if you don't apply soon.

·    We can use unless to mean 'if not' in the first conditional: Unless I do it now, I'll be too old. = If I don't do it now, I'll be too old.

Zero conditional; conditionals with modal verbs and imperatives, in case

Zero conditional

·    The zero conditional talks about things that are always true :

If you have children, you worry about them all the time.

·    In the zero conditional both verbs are in the Present Simple: If children stay indoors all the time, they become unfit.

*If and when have the same meaning in the zero conditional: If/When I'm worried, I don't sleep very well.

Zero or first conditional

Compare these sentences:

If the children aren't home by five, I call the school.

This sentence is a zero conditional. It talks about something that is always true.

If the children aren't home by five, I'll call the school.

This sentence is a first conditional. It talks about one specific time in the future.