which

which [ wıtʃ, hwıtʃ ] function word ***

Which can be used in the following ways:

as a determiner (followed by a noun):

Which color do you like best?

as a pronoun (without a following noun):

Choose any card it doesn't matter which. (introducing a question):

Which is the hottest month of the year? (followed by of ):

Which of you is responsible for this department? (introducing a relative clause):

My car, which I have owned for five years, is a Ford.

1. ) used for asking for a specific choice from a limited number of possibilities:

Which would you like, tea or coffee?

Which way did they go?

which of: Which of the secretaries did you talk to?

a ) used when someone knows, says, is not certain about, etc. the specific choice between two or more possibilities:

They're all so pretty I don't know which one to choose.

It was either whisky or vodka I forget which.

Did he say which hotel he was staying at?

I don't know which is worse spending Christmas alone or watching my friends get drunk.

2. ) used for adding information or a comment about a particular thing or fact when it is already clear what that thing or fact is:

Bogart starred in the film Casablanca, which was made in 1942.

A skilled workforce is essential, which is why our training program is so important.

The search will not begin until dawn, by which time it will probably be too late.

in which case (=if this happens): Of course it may rain, in which case we'll have to hold the ceremony indoors.

3. ) => NOTE used for introducing information that shows what specific thing or type of thing you are talking about. It is more usual and considered better to use that to introduce this type of relative clause:

I've been thinking about those questions which you asked me last week.

It's a story which every child will enjoy.

the air crash in which Hammarskjöld died

know/tell which is which

to be able to see the difference between two or more similar things:

They look exactly alike to me. How can you tell which is which?