Question

What do you do when it _____?
--- I often stay at home and read books.

A．raining

B．rain

C．rains

D．is rains

Answer 1

C

考察时态。when引导时间状语从句。从句描述的是反复性的动作，故用一般现在时态。主语是it，单数第三人称，故谓语动词要用单数形式。选C。