英语语法一点解答谁能帮我区分一下英语语法"情态动词+have done"中can have done;can't have done;could have done ;couldn't have done ,5年高考3年模拟那本书把我讲的糊里糊涂的,脑子左半边是水,右半边是面粉,搅成糨糊了!
问题描述：
英语语法一点解答
谁能帮我区分一下英语语法"情态动词+have done"中can have done;can't have done;could have done ;couldn't have done ,5年高考3年模拟那本书把我讲的糊里糊涂的,脑子左半边是水,右半边是面粉,搅成糨糊了!
答
could (不能用 can) have done 表示“过去本能够做某事却未做.”
注意：其否定形式 couldn't have done 没有虚拟语气的用法,
couldn't have done 只能表推测,相当于 can't have done,
意为：“过去不可能做了某事.”
当表示推测时候 can/could have done 一般用在否定句和疑问句中,表示不相信或怀疑的态度.