I am reading in Longman Dictionary of Contemporary English. They wrote:
WORD CHOICE: unless, if ... not
Use 'unless' to say that something will happen or be true if something else does not happen or is not true : Unless they get protection, they will not testify.
!! Do not use the future tense after 'unless' : I won't go unless you go (NOT unless you will go).
!! Do not say 'unless if' : Don't call him unless it's urgent (NOT unless if it's urgent).
Use 'if ... not' when you know that something did not or will not happen : If he had not tripped, he would have won (=but he didn't win). |: I would go out if it wasn't raining (=but it is raining, so I am not going out).
I am wondering if 'unless' and 'if ... not' have the same meaning.
Can I replace 'if ... not' with 'unless' in the following sentence?
If he had not tripped, he would have won?
Unless he had tripped, he would have won?
Thank you very much.