Frequency: The word is one of the 700 most common words in English.
1.
You use which in questions when there are two or more possible answers or alternatives.
Which do they want me to do, declare war or surrender?...
Which are the ones you really like?...
'You go down that passageway over there.'-'Which one?'...
Which vitamin supplements are good value?
QUEST
2.
You use which to refer to a choice between two or more possible answers or alternatives.
I wanted to know which school it was you went to...
Scientists have long wondered which parts of the brain are involved in musical tasks.
DET
•
Which is also a conjunction.
In her panic she couldn't remember which was Mr Grainger's cabin...
There are so many diets on the market, how do you know which to choose?
CONJ
3.
You use which at the beginning of a relative clause when specifying the thing that you are talking about or when giving more information about it.
Soldiers opened fire on a car which failed to stop at an army checkpoint...
He's based in Banja Luka, which is the largest city in northern Bosnia...
Colic describes a whole variety of conditions in which a horse suffers abdominal pain...
PRON
4.
You use which to refer back to an idea or situation expressed in a previous sentence or sentences, especially when you want to give your opinion about it.
Since we started in September we have raised fifty thousand pounds, which is pretty good going...
PRON
•
Which is also a determiner.
The chances are you haven't fully decided what you want from your career at the moment, in which case you're definitely not cut out to be a boss yet!
DET: DET sing-n
5.
If you cannot tell the difference between two things, you can say that you do not know which is which.
They all look so alike to me that I'm never sure which is which...
PHRASE: V inflects
6.