English lesson_whether-if

whether - if

          Whether and if can both be used in the following cases:

         1) To express alternatives :
               ▪ I don't know whether/if I'll go to the party (or not).

          2) To report a question :
               ▪ Are you going to the party?
                  → She asked me whether/if I was going to the party (or not).

          Only whether can be used in the following cases :

        1) When followed by an infinitive :
                ▪ I don't know whether to go to the party or not.

2) After prepositions :
▪ It depends on whether I get home early or not.

3) When whether begins a clause which is the subject of a sentence :
▪ Whether I go to the party or to the cinema makes no difference to me.

4) When followed directly by 'or not':
▪ I'll be happy whether or not I go to the party.