This head must have been found in Classical times and carefully preserved此句摘自《新概念英语》第三册，第三篇《无名女神》。主语this head是属于第几人称，为什么用"have been"而不是用"has been“?

This head must have been found in Classical times and carefully preserved此句摘自《新概念英语》第三册，第三篇《无名女神》。主语this head是属于第几人称，为什么用have been而不是用has been“? this head must have been found in classical times and carefully preserved.后句preserved用的是被动语态么?为什么不是and carefully have been preserved的? 句子省略This head must have been found in Classical times and carefully preserved.这里and后面是不是省略了it is,为什么能这样省略,类似的句子是不是都能这样省略? 英语翻译基本无误就可以、谢了!Pull the hand of the hand,This whole life must togetherThe Road to accompany each other,don`t have turn head leeway这样翻译有没有语法上的错误? I must have aide sinmy head for ever的汉语意思是什么? this is my head have a head 用big this have boy a head does 号 连句 must have he must have read this book yesterday用完成?he must read this book yesterday?才对吧 一道完成句子she knows this place so well ,she (must have lived) here.为什么不用must have been lived? 英语翻译1.……paused a moment in his writing to glance loviongly at the black head bent over the peppers.2.Never mind.I must rewrite the passage.Possibly it has got torn up,and I have kept you all this time for nothing. he must have read this book yesterday?反问?did not he?have not he?为什么 I discover you head have I found this book when Icame to the classroom.It must must have been left by one the students You must have ArcGIS Engine installed in order to execute this system. To do this job,you must have a degree in English英文翻译成汉语! Someone must have taken it away this morning,___?为什么填didn't he Thankyou!