Structure[edit | edit source]
This structure is often used for things like the laws of physics. This is in general time (i.e. past, present and future) and applies to things that often or repeatedly happen. For example:
- "If you heat water to 100 degrees at standard pressure, it boils."
- "When I get an email, I read it."
- Is this in the past/present/future (all three, so general time)
- Does this happen once or many times? (many times)
- Can we replace "if" with "when"/"each time"/"every time"? (usually, yes).
Replacing "if" with "when"[edit | edit source]
We can replace "if" with "when" if something happens repeatedly. We can't do this with the first conditional. However, if and when have slightly different meanings, and one or the other may be more appropriate. We can't use "when" if there is a significant delay between the condition and the consequence.
Complications[edit | edit source]
Note that generally we don't use "will" or "going to" with the zero conditional, and certainly not in pedagogic examples, but they’re not completely excluded. "Will" can express certainty, or delay. This, in theory can lead to syntactically ambiguous sentences, but usually it doesn't matter, as the ambiguity would be pragmatically clear. For example:
- "If I get a phone call I will definitely always answer it."
- "If I receive an email overnight, I will read it in the morning."
There are also some overlap circumstances in which either the zero conditional or the first conditional would be appropriate.