Both are "correct". They just have different subjects.

Both are "correct". They just have different subjects.

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LONG ANSWER VERSION: Let's identify the subject of each interrogative clause, by using the verb's number as the indicator:

?1.a) Which one is you?


?2.a) Which one are you?


Notice that there is formal subject-verb agreement between the subject and verb in each version.

Let's verify that we've actually identified the subject, by looking at a related declarative clause for each of those above two interrogative clauses.

For #1.a. "Which one is you?":
?1.b) That one is you. -- [declarative clause]
?1.a) Which one is you? -- [interrogative clause]

The conversion from declarative #1.b to the interrogative #1.a was a straightforward change from "That one" to "Which one". The subject of both versions are before the verb.

For #2.a. "Which one are you?":
?2.b) You are that one.
?2.c) You are which one? -- [interrogative clause, interrogative phrase in situ]
?2.a) Which one are you? -- [interrogative clause, fronted interrogative phrase]

Notice that when the interrogative phrase ("which one") is fronted in a main clause, that causes obligatory subject-auxiliary verb inversion. That is what happened between the last two steps.

To verify this, we can use a multi-word verb phrase to see this subject-auxilary verb inversion working:

?3.a) You would be that one.


?3.b) You would be which one?


?3.c) Which one would you be?


Notice how the subject "you" ended up getting sandwiched between "would - be".

A similar exercise can be done with the subject "Which one", except there is no subject-auxiliary verb inversion because the interrogative phrase is the subject:

?4.a) That one would be you.


?4.b) Which one would be you?


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Short story: One way to find the subject of an interrogative main clause is to convert the example sentence into one that uses a multi-word verb phrase. The subject will either be in the front before the verb phrase, or else it will be sandwiched in between the verbs.

Using the OP's two examples:


?1.) Which one is you?


?2.) Which one are you?


we see that the versions can be converted into the below:


?1.x) Which one will be you?


?2.x) Which one will you be?


Since the OP's two examples only had a single verb in them ("is" vs "are"), then as to what the subject is will, in this case, depend on the verb that is used -- for the speaker/writer will have used subject-verb agreement between the subject and verb.

So, the answer is: Both are "correct". They just have different subjects.

所有跟帖： 

• 那“who are you?" vs "who is you?"呢？ -決不撒謊- ♂ (0 bytes) () 06/12/2015 postreply 18:55:14

• 扯蛋，who is I 也行？ -查無此人- ♂ (0 bytes) () 06/14/2015 postreply 22:21:33

• Who am I and which is me are two different things. -網球伯- ♀ (0 bytes) () 06/16/2015 postreply 17:05:32