表示否定推测只能用can't 和 couldn't

问题描述:

表示否定推测只能用can't 和 couldn't

1.对现在情况的推测:must/can't be; must/can't be doingHe must be in the library.He can't be in the classroom.(他一定是在图书馆.他不可能在教室里.)She must be doing her homework.She can't be watching T...