he can't have been Danish.he must have been Swedish.

he can't have been Danish.he must have been Swedish. She can't have been Danish. and She must have been Swedish. He can't have been.He must have been.不是说单三用has吗? he can't haue been a dcntist.he must have been a doctor. He can't have been ill. He must have been ill,___ he? Edison must have been very clever,wasn’t he? can't have been和must have been He must have been的用法. he must have been there before----- 英语：助动词的问题he must（can't may等） have been asleep,就有两个助动词,must , He can't have been ill是现在完成时?