Last month she explained to one of her classes about sound,and she decided to test them to see how

问题描述:

Last month she explained to one of her classes about sound,and she decided to test them to see how
后面是successful she had been in her explanation

上个月,她在她其中一节课解释关于声音,而且她决定测试一下他们来看看他的解释到底有多成功.