is your mother’s birthday?It’s on 1 August.A. WhereB. WhenC. WhatD. Which

问题补充：

--- is your mother’s birthday?

--- It’s on 1 August.

A. Where

B. When

C. What

D. Which

答案：

A. Where

(答案→)B. When

C. What

D. Which

解析：Where在哪儿;When什么时候;What什么;Which哪一个.根据答语,在八月一日.可知上文问的是时间,故选B.