They can’t have been doing their homework--句中“can't"是不是可以直接去掉,从语法上来讲没有错啊?还有They can’t have been doing their homework能改成：They haven't been doing their homework
问题描述：
They can’t have been doing their homework--句中“can't"是不是可以直接去掉,从语法上来讲没有错啊?
还有They can’t have been doing their homework能改成：
They haven't been doing their homework
答
They haven't been doing their homework 从语法上说这样是完全服合逻辑的.
至于They can’t have been doing their homework从口语上理论也算对的.如果是肯定式的话,can’t是完全可以去掉的.
祝你越学越精彩哦.