__we could not have finished the work on time.A should they not offer to help us B but for their help 想知道A错误在哪里,如何改.答案是B.

__we could not have finished the work on time.A should they not offer to help us B but for their help 想知道A错误在哪里,如何改.答案是B. could not have done 谁知道could not have These first dogs were not like __we have know A.what B.which同上 must not have been;could not have I wonder __we could have a talk after the meeting .A which B why C that D if Could not help but have to can not have visited could have visited must have visited should not have visitedcan not have visitedcould have visitedmust have visited should not have visited （一定要说明原因）---Excuse me,could you tell me __we'll have a meeting next Monday?---Sorry,I don't know.You may ask the teacher.A.that B.if C.what D.how In fact,you did not know they could have been could not could not If it _ for the rain,we _ the picnic yesterday.A were not; could have hadB were not; could haveC had not been; could have had 请问could not have done/might not have done可用于虚拟语气中吗 May not have done 是表示可能不还是不可能 那Could not have done呢 1should not have done 2 could not have done 3 would not have done 有什么区别 could never have done和could not do有什么区别 lily could not have accepted the invitation-----?为什么用has she 不是could she