The correct answer is: A. Had not/are you.
The reason is that the sentence is in the past tense, and the speaker is expressing surprise at not having seen the listener for a long time. The past perfect tense (had not seen) is used to express an action that happened before another action in the past. The present tense (are you) is used to ask a question about the present.
The other options are incorrect because they do not use the past tense. Option B, Have not/have you been, uses the present perfect tense, which is used to express an action that started in the past and continues into the present. Option C, Did not/had you been, uses the past simple tense, which is used to express an action that happened at a specific time in the past. Option D, Have not/are you been, uses the present tense twice, which is grammatically incorrect.
Here is a more detailed explanation of each option:
- Option A: Had not/are you. This is the correct answer because it uses the past perfect tense (had not seen) to express an action that happened before another action in the past (are you). The past perfect tense is used to express an action that happened before another action in the past. In this case, the speaker is expressing surprise at not having seen the listener for a long time. The past perfect tense is formed with the past participle of the verb (seen) and the auxiliary verb had.
- Option B: Have not/have you been. This is an incorrect answer because it uses the present perfect tense (have not been) to express an action that started in the past and continues into the present. The present perfect tense is used to express an action that started in the past and continues into the present. In this case, the speaker is expressing surprise at not having seen the listener for a long time. The present perfect tense is formed with the present participle of the verb (been) and the auxiliary verb have.
- Option C: Did not/had you been. This is an incorrect answer because it uses the past simple tense (did not see) to express an action that happened at a specific time in the past. The past simple tense is used to express an action that happened at a specific time in the past. In this case, the speaker is expressing surprise at not having seen the listener for a long time. The past simple tense is formed with the base form of the verb (see) and the auxiliary verb did.
- Option D: Have not/are you been. This is an incorrect answer because it uses the present tense twice, which is grammatically incorrect. The present tense is used to express an action that is happening now. In this case, the speaker is expressing surprise at not having seen the listener for a long time. The present tense is formed with the base form of the verb (see) and no auxiliary verb.