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QUESTION
How can i explain to my students when to use 'if' or 'whether' -- for
example, when they are interchangeable and when they are not. Is there
a specific rule that governs the usage?
GRAMMAR'S RESPONSE
According to the New York Public Library's Writer's Guide to Style and
Usage, "if" and "whether" are "interchangeable as long as the meaning
is clear and the construction is sensible." I don't find that
particularly helpful, myself, but that guide then goes on to say that
either "if" or "whether" can be used after such verbs as ask, doubt,
hear, and know: "Did you ask if/whether we had to be present to win?"
and that "whether" is considered the more formal of the two. "Whether"
is preferred at the beginning of a sentence to introduce a noun
clause: "Whether he had a chance to win the election was a subject of
considerable debate."
Authority: New York Public Library Writer's Guide to Style and Usage
HarperCollins: New York. 1994. Cited with permission. p. 72.
http://grammar.ccc.commnet.edu/grammar/grammarlogs3/grammarlogs470.htm
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