MUST have been done
问题描述：
MUST have been done
must have been doing
must have been +名词
must have done
以上的区别
还有是否有must have been done 的用法 和区别
EG1 I must have been sleeping
2 your dress must have been expensive.
3 I didn't hear the phone,I must have been alseep
答
其实must have been done只是must have done的被动形式罢了.
我说,你举出来的那几个例子：1那个就是must have been doing的结构是指某动作在过去某时间点开始,一直持续到现在,有继续持续下去的趋向,或者等这句话一说完这个动作就完成；
2那个是加形容词 be expensive=很贵,must have been expensive= 一定是很贵的了.
3那个asleep也是形容词,be asleep=睡着的.句子意思是：那时我一定是睡着了.（表示对过去肯定的推测）