Page 642 - Practical English Usage 3ed - Michael Swan, Oxford

619 where (to)
To is often dropped after where.
Where are you going (to)? Where does this road lead (to)?
To is not normally dropped in the short question Where to? Could you send this offfor me?- Where to?
For where in relative clauses, see 494.10
620 whether ... or ...
We can use whether . .. or . .. as a double conjunction, with a similar meaning to It doesn't matter whether . .. or ...
The ticket will cost the same, whether we buy it now or wait till later.
Whether we go by bus or train, it'll take at least six hours. Several structures are possible with whether . .. or not.
Whether you like it or not, .. .
Whether or not you like it, .. .
Whether you like it or whether you don't, ...
For whether and if. see 621.
621 whether and if
1 indirect questions
Whether and ifcan both introduce indirect questions. I'm not sure whether/ifI'll have time.
I asked Whether/if she had any letters for me.
After verbs that are more common in a formal style, whether is preferred. We discussed whether we should close the shop.
(More normal than We discussed if...)
In a formal style, whether is usually preferred in a two-part question with or.
The Directors have not decided whether they will recommend a dividend or reinvest the profits.
If an indirect question is fronted (see 513), whether is used. Whether I'll have time I'm not sure at the moment.
2 prepositions
After prepositions. only whether is possible.
There was a big argument about whether we should move to a new house.
(NOT ••• ttb6ftt if1m] aiMftid "ttwe ...)
I haven't settled the question o/whether I'll go back home.
3 infinitives
Whether, but not if, is used before to-infinitives. Theycan'tdecidewhethertogetmarriednoworwait. (NOT Theyedlt'ttleetde
:--' ) lJ te get "ttt1'l'reu . . .
.~
where (to) 619
page 610