17.1. |
If/When + present simple, present simple |
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PRESENTATION |
Use if/when + present simple, present simple to talk about facts or things which are generally true.
| if-clause | main clause | ||||
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This is sometimes called the zero conditional. |
if or when?
In sentences about general facts, there is little or no difference in meaning between if or when.
If a mosquito bites you, it’s usually a female. = When a mosquito bites you, it’s usually a female.
(See also note on if and when in Unit 17.3.)
Punctuation
When the sentence begins with the if-clause, put a comma after the if clause:
If you heat water to 100 degrees, it boils.
When the sentence begins with the main clause, don’t use a comma:
Water boils if you heat it to 100 degrees.