英语 用所给动词的适当形式填空. We all ---------(clap) hands when we saw Shenzhou VII launching

问题描述:

英语 用所给动词的适当形式填空. We all ---------(clap) hands when we saw Shenzhou VII launching
into space.
用clapped还是were clapping

clapped为什么不用were clapping