which
which — determiner
1. used in questions when you are asking someone to pick one person or thing from a
used in questions when you are asking someone to pick one person or thing from a limited number of possibilities
Which flavor do you want — chocolate or vanilla?
which + noun in a choice question
Jude asked the librarian which book the class should read first.
indirect question after asked
Which bus goes to the train station from here?
The travel agent asked Henrik which dates worked best for his vacation.
- what
Used when the set of possible answers is open, not limited — e.g., 'What book are you reading?' (any book), vs. 'Which book…?' (from a known set).
文法句型
which + noun + (modal) + verb
用法筆記
The answer is expected to come from a set of known options — unlike 'what', which is used when the options are open or unknown. Frequently used with 'of' (which of the…).
常見錯誤
2. used to make clear or ask about the exact identity of a particular person or thi
used to make clear or ask about the exact identity of a particular person or thing among several
Rin showed the new student which desk was hers.
show + which + noun + clause
The doctor asked the nurse which arm the patient had injured.
ask + which + noun in embedded question
I cannot remember which street leads to the old market.
Eshe checked the timetable to see which train left before 8 a.m.
- which one
Used as a pronoun instead of a determiner — e.g., 'I know which one she picked' vs. 'I know which dress she picked.'
文法句型
know/say/see/remember + which + noun + clause
用法筆記
Common after verbs of knowing, showing, telling, and deciding. Unlike sense 1 (direct question), this sense often appears in statements or indirect questions where the speaker is identifying rather than asking.
常見錯誤
3. used after a preposition to connect a clause that gives extra information about
used after a preposition to connect a clause that gives extra information about a time, event, or thing just mentioned in the previous clause
The storm lasted all night, during which time the power went out twice.
during which time — formal relative determiner
Walid studied in Taiwan for three years, after which period he returned home.
after which period — linking time phrase
The company lost its main client, as a result of which event half the staff were let go.
Daichi paid the deposit on Monday, by which date the discount was still available.
文法句型
preposition + which + noun + clause
用法筆記
Frequently used in formal or written English. The preposition (during, after, before, by, in, on, at, for, as a result of) comes before 'which', and together they modify the noun that follows. In informal speech, this construction is often replaced with simpler structures.
常見錯誤
which — pronoun
1. used in questions when you are asking someone to choose one or more people or th
used in questions when you are asking someone to choose one or more people or things from a limited set, without repeating the noun
Which of these jackets do you think would be warmer for a snowy day?
which + of + [group] expanded question
Asher has three cousins, but I cannot guess which is the eldest.
Which would you like to drink — juice or tea?
The taxi driver asked which of the two addresses was our final stop.
- what
'What' is used for open-ended choices — 'What do you want to eat?' (no limit) vs. 'Which do you want?' (from a limited menu).
文法句型
which + of + group noun / pronoun
用法筆記
Unlike the determiner sense (which + noun), this pronoun sense stands alone as the subject or object. It is almost always used with a limited set that is clear from context or introduced by 'of'.
常見錯誤
2. used as the subject or object of a relative clause to refer back to a thing, ani
used as the subject or object of a relative clause to refer back to a thing, animal, or idea already mentioned, adding more information about it
The movie, which Ramón had already seen twice, was still exciting.
noun + comma + which + non-restrictive clause
Linh's old bicycle, which she had owned since high school, finally broke down.
The report which Pim wrote in one night won the company award.
The package arrived in a box which was much bigger than the item inside.
- that
Can replace 'which' in restrictive clauses (no commas) — 'the book that I read' vs. 'the book which I read.' In non-restrictive clauses, 'that' is informal in British English and incorrect in American English.
文法句型
noun + which + relative clause
用法筆記
For people, 'who' or 'whom' is preferred over 'which'. 'That' can replace 'which' in restrictive (no comma) relative clauses, but not in non-restrictive (with comma) clauses. 'Which' refers to the immediately preceding noun, not to the whole clause — for clause reference, see the determiner relative sense.
常見錯誤
3. used in the pattern 'which is which' when talking about being able to see or exp
used in the pattern 'which is which' when talking about being able to see or explain the difference between two or more similar people or things
The twins look so alike that nobody can tell which is which.
tell which is which — fixed idiom for distinguishing
The teacher mixed up the test papers and could not tell which was which anymore.
All the keys on the desk look identical, so Christopher marked them to know which is which.
The wine bottles had no labels, so the waiter could not tell which was which before serving.
文法句型
tell/know + which + is + which
用法筆記
The phrase 'which is which' is the most common form and is a fixed expression. The first 'which' refers to one set of items, the second 'which' to the other set. This sense is very common in everyday speech when items are nearly identical.
常見錯誤
which — adjective
1. any one that; no matter which one — used before a noun to say that the choice do
any one that; no matter which one — used before a noun to say that the choice does not matter
Take which seat you want — they are all free.
which + noun + clause = whichever, any that
Jabari told his guests to take which room they preferred for the night.
Choose which route you like best for the weekend hike.
The children were told they could pick which game they wanted to play first.
- whichever
The modern, more natural alternative to this sense — 'Take whichever book you like' is more common than 'Take which book you like.'
文法句型
which + noun + verb (any that…)
用法筆記
This sense is less common in modern everyday speech, where 'whichever' is more typical. It survives in formal or literary styles. The clause after 'which' acts like a free relative, giving the listener full freedom of choice.