A pattern of the zero conditional
If + present simple tense, present simple tense
Examples
If you heat ice, it melts.
= When you heat ice, it melts.
If metal gets hot, it expands.
The boy cries if you scold him.
It means when the condition is met, the result is 100 percent produced.
The other pattern is rare:
If + past simple tense, past simple tense.
If the kids didn't pass the examination, they failed the grade.
It means when the condition was met in the past, the result was 100 percent produced.
