The teacher says the windows need ----- .A mending B mends C

A
解释如下
need 接动名词主动形式,表示被动意义、这时动名词和主语之间有动宾关系, need doing 可转换为 need to be done 结构,意思相同.如：
My hair needs washing badly. (= My hair needs to be washed badly.)
我的头发非常需要洗一洗.
The garden needs watering. (=The garden needs to be watered.)
花园需要浇水.