which -
adj. & pron. --interrog.adj. asking for
choice from a
definite set of alternatives (
which John do you mean?; say
which book you prefer;
which way shall we go?). --rel.adj. being the one just referred to; and this or these (ten years, during
which time they admitted nothing; a word of advice,
which action is within your power, will set things straight). --interrog.pron.
1
which person or persons (
which of you is responsible?).
2
which thing or things (say
which you
prefer). --rel.pron. (poss. of
which, whose)
1
which thing or things, usu. introducing a clause not essential for identification (cf. THAT pron.
7) (the house,
which is empty, has been damaged).
2 used in place of that after in or that (there is the house in
which I was born; that
which you have
just seen).
which is which a phrase used when two or more persons or things are difficult to distinguish from each other. [OE hwilc f. Gmc]