她给孩子们脱了衣服，然后把他们放上床睡觉。

She ___undressed the children and put them to bed.

这把椅子是我脱衣服时放衣服用的。

The chair is for my clothes when I ___undress.

他洗澡前迅速脱了衣服。

He quickly ___undressed before taking a shower.