–Have you studied English for a long time?--Yes I have studied it .A. five years beforeB.

问题补充：

–Have you studied English for a long time?

--Yes, I have studied it .

A. five years before

B. five years ago

C. for five years

D. since five years

答案：

A. five years before

B. five years ago

(答案→)C. for five years

D. since five years

解析：完成时态通常和时间长度连用，只有C表示时间长度，故选C。