must have been在主句是一般过去式的宾语从句中变为must had been吗 ?两小时内给出答案

must have been在主句是一般过去式的宾语从句中变为must had been吗 ?两小时内给出答案 must have been请问 must have been 是推测某人一直在做某事吗? 在英语里coms been、must been和may been和come have been、must have been和may have been的区别?请举例!哪些词是宾语、定语、介词,请举例!coms应该是comes must have been done must have done must have/ must have been的区别 Life must have been difficult when you were a kid.句子分析从句when you were a kid是个明显表示过去的从句,那么主句为什么用现在完成时“have been ...”呢?为什么不说：Life must be difficult when you were a kid. He must have been away 哪个是情态动词 是must还是have同上 must not have been;could not have must have been在美语中的连读这句话在句子中听到的好象是must a been,也就是说have的h和ve都省略了,请问是这样吗,请帮忙回答,谢啦. must have donemust have done 的用法详细说明.可以归结为虚拟语气里面的么?must have been down 是must have down 的被动语态么 must have been与must have done的区别? must be和must have been 在句子中作什么成份及其时态?must be算是must+系动词么?如果后面加doing就算是现在进行时?must have been 本身可以算是现在完成时么?如果后面加doing就算是现在完成进行时么?是 ABAQUS中出现如下错误,一般是由于什么原因造成的!Node set assembly__pickedset26 has not been definedUnable to locate node set assembly__pickedset26. The node set must have been previously defined. There have been 一般疑问句 by the end of +过去时.主句用过去完成时.如果是现在一般时.主句什么时态?will have done形式哪时候用 have to和must怎么变成一般疑问句（是have to不是have） He must have been的用法.He must have been它的后面可以跟哪几种类型的词语?如果我想要表达“那时他一定在家里”。He must have been at home.must have been 有must had been 这种说法吗？如果有表达的又是什么 It Must Have Been Love (Cologne) 歌词