---Your Japanese is so good. How long have you been in France?- I was five.A. Since B.

问题补充：

---Your Japanese is so good. How long have you been in France?

--- I was five.

A. Since

B. Before

C. Until

D. When

答案：

(答案→)A. Since

B. Before

C. Until

D. When

解析：since+点时间表示从···以来，常用来回答how long引导的疑问句。