What is the difference between "whether" and "if"?

English as a Second Language English Vocabulary, Grammar and Idioms
1

Please read:

  1. I asked him whether he had done all the work himself or whether he had had any assistance.
  2. I asked him whether he had done all the work himself or he had had any assistance.
  3. I asked him if he had done all the work himself or if he had had any assistance.
  4. I asked him if he had done all the work himself or he had had any assistance.

I think all are correct? Am I right?

Quoc

2

Yes, Quoc, but I would repeat the conjunction for each choice:

I asked him whether/if he had done all the work himself or whether/if he had had any assistance.

3

Hi,

Whether hints at the idea of yes or no. I asked him if he had finished is simply the indirect version of: Have you finished? I asked him whether he had finished is more open and suggests: Have you or haven’t you?

Alan