can't／couldn't be doing sth是表示现在进行时吗

can / could be doing sth，can't / couldn't be doing sth是表示现在进行时吗? can't和couldn't怎么选呢?

can't/ couldn't be doing sth 都是情态动词的推测性用法，表示说话人推测某件事不可能或者不太可能正在发生。如果说话人推测时信息很足，认为绝对不可能某事正在发生，就用can't be doing. 如果自己推测的准确性只有60%左右，则用couldn't be doing.

Tom can't be sleeping now. I saw him in the supermarket five minutes ago. 不可能

Tom couldn't be sleeping now. He has lots of homework to do. 不大可能

曹荣禄 -

擅长：动词用法,句法问题 | 采纳率 82% | 回答于 2021-11-16 16:11

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黎反修 - 英语翻译（已退休） 2021-11-16 15:14

擅长：数词用法,存在句,英语考试