The zero conditional is used to describe something that is always true. The two parts that make up the zero conditional sentence have the same tense: simple present.
if + present simple (conditional clause) | Present simple (main clause) |
If I mix yellow with blue, | I get green. |
If you draw back the curtains, | you let the sunlight in. |
The positions of the two clauses above are not fixed. In other words, they can change places.
present simple | if + present simple |
I get green | if I mix yellow with blue. |
You let the sunlight in | if you draw back the curtains. |
When/whenever can be used instead of if.
Examples:
-
If/When I mix yellow with blue, I get green.
We can use the past simple instead of the present simple as above. The past simple must be used in both clauses.
Examples:
- If he called her, she always said she was busy.
- If I bet on a horse, the horse often came last.