Question

You know that Jane is a good friend of Carol’s.
You ask Jane:- ___________________. (how long/ know/ Carol?)
A) How long do you know Carol?
B) How long did you know Carol?
C) How long have you known Carol?
D) How long have you been knowing Carol?

Answer 1

Hint:Verb tense is a tense of a verb that is determined when the action took place. Basically, tenses are of three types: past tense, present tense and future tense. For example:-
Past tense – I ran; present tense – I run; future tense – I will run.

Complete answer:
To fill the blank meaningfully and grammatically correct, we should first understand the Present perfect tense. Present perfect tense is the combination of the present and the perfect tense i.e. it is used to express a past event that has present consequences. For example: He has lived here all his life.
Option A) How long do you know Carol? – is an incorrect answer because ‘How long do you know Carol?’ is describing a routine or habit. Thus, this option does fit correctly in the blank. Therefore, this is an incorrect answer.
Option B) How long did you know Carol? – is an incorrect answer because ‘How long did you know Carol?’ indicates the past action and we need our answer in present perfect tense. Therefore, this is an incorrect answer.
Option C) How long have you known Carol? – is the correct answer because ‘How long have you known Carol?’ is in the present perfect tense and the statement in this option describes the action of knowing Carol which is till not stopped. Therefore, this is the correct answer.
Option D) How long have you been knowing Carol? – is an incorrect answer because ‘How long have you been knowing Carol?’ it refers to the continuous action but 'to know someone' is a short action, we don't use the continuous form 'knowing' in the blank. Therefore, this is an incorrect answer.

The correct answer is (Option C).

Note:The present perfect tense is a verb tense which is used to describe an action that has taken place once or many times before now i.e. knowing Carol. The present perfect is formed using has/have + past participle, here, "have known". Hence, Option C is correct and the other options do not adhere to this condition.