谁知道could not have

谁知道could not have could not have done must not have been;could not have 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 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 谁知道 Download failed because the谁知道 Download failed because the resources could not found 求答. 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 情态动词加上完成时的意思?could not have done must not have done should not have done would not have done 以及它们的用法? 【高一英语】If it____for the snow,we____the mountain yesterday.A.were not ;could have climbedB.were not ;could climbC.had not been ;could have climbedD.had not been ;could climb答案：CA为什么不对呢? 谁知道I be afraid not have you的中文意思