－do you go to the library?－Once a week.A. How longB. How soonC. How often D. How many time

问题补充：

－do you go to the library?

－Once a week.

A. How long

B. How soon

C. How often

D. How many times

答案：

A. How long

B. How soon

(答案→)C. How often

D. How many times

解析：通过答语Once a week“一周一次”可以判断本句是问频率的，答案应选C。How long “多长时间”，How soon“多久”‘How many times“多少次”