Possible Duplicate:
When are “if” and “whether” equivalent?
I was told that one can use if in constructions like:
... if A, then ...
But that whether should be used when there is more than one option, like:
... whether A or B, then ...
Is it good practice or common to use whether when giving only one implicit or explicit option?
... whether A (or not), then ...
... whether A, then ...