UC知道They can’t have been doing their homework ---doing是什么词性？ have been 在这里还是表现在完成时吗
来源：百度知道 编辑：UC知道 时间：2024/09/21 22:36:28
doing是do的进行式哈，不是词
have been doing是完成进行时，意即：他们不可能现在还在忙着他们的作业
他们现在不可能正在做作业
表示完成时，doing表示在过去一段时间里一直在干,是分词。
现在完成进行时 表示从过去的一个时点到现在持续的做一件事情。
例如：I have been cooking for 3 hours.表示3个小时前我就在做饭，现在还在做。
doing非谓语动词,现在分词
They can't have been watching the football match this time yesterday,___?
They can can what they can can,but can't can what they can't can是什么意思
can't have been
They must have arrived by now,haven't they?
they are [ ] children that they can't dress themselves.
they can help peopleto w_____out many problems they can't do easily.
They say you can’t judge a book by
They can't understand what the foreigners say,they can't read English books and newspapers.
They didn't do as well as they should have
can I have ____water?No you can't have ____.