by Alan » Fri Sep 17, 2004 10:19 am
'Whether' is a conjunction having the meaning 'if...(or not)' that can introduce two types of clause:
(1) nominal clauses, as in
I don't know WHETHER she's going to come tomorrow.
(2) concessive adverbial clauses, as in
WHETHER it's sunny or not, we'll still go out!
Note that:
1. In type (1), 'whether' can be replaced by 'if'.
2. In type (1) the words 'or not' are redundant, although - on account of confusion with type (2), where they are obligatory - native speakers often add them.