其實(shí)must have been done只是must have done的被動(dòng)形式罷了.
我說,你舉出來的那幾個(gè)例子：1那個(gè)就是must have been doing的結(jié)構(gòu)是指某動(dòng)作在過去某時(shí)間點(diǎn)開始,一直持續(xù)到現(xiàn)在,有繼續(xù)持續(xù)下去的趨向,或者等這句話一說完這個(gè)動(dòng)作就完成；
2那個(gè)是加形容詞 be expensive=很貴,must have been expensive= 一定是很貴的了.
3那個(gè)asleep也是形容詞,be asleep=睡著的.句子意思是：那時(shí)我一定是睡著了.（表示對(duì)過去肯定的推測(cè)）