where must the puma have come from 其中must have done是什么用法?

where must the puma have come from 其中must have done是什么用法? 新概念第三册的第一课:where must the puma have come from?第三册的第一课where must the puma have come from? where must the puma have come from?请仿照这个句型造几个句子.请附带中文意思.. where must the puma have come from,怎么翻译,有的说 must have done,可是come不是done的形式啊? where must the puma have come from?对过去的事进行推测,疑问句和否定句中要用can和can't.这句话中的must是不是用错了? 现在完成时疑问句只用have?今天看新概念第三册的第一课.课文前的问题是：Where must the puma have come from?为什么用have 疑问句一定用have? 英语高手请进 where must the puma have come from?这是什么句型,为什么must后面不要加be的,为什么要加have?which are found in american?为什么要加areas the evidence began to accumulate ,began to accumulate是什么意思,为 puma puma The experts from the zoo were convinced that the animal was a puma,but where had it come from 为什么不用where did it come from Y This is where the oil must be The experts were fully convinced that the animal ________a puma.A:must be B:should have been C:can only be D:could only have been我自己感觉应该是选择A课文里面有一句话The experts were fully convinced that the animal was a puma.所以 新概念3中第一课 A puma at large中,HAVE的用法疑惑新概念3中第一课 A puma at large中,有一句话：As no pumas had been reported missing from any zoo in the contry,this one must have been in the possession of a private collector an 新概念上的一道选择题The experts were now fully convinced that the animal_______a puma.A.must be B.should have been C.can only be D.could only have been可能是多项选择,是A和D么 英语里面,表示谁的什么,一般用’s或者of,可puma fur为什么不用puma's fur?不懂这个怎么用,在我看来,应该是puma's fur或者the fur of a puma吧 这句话china must be the place where the hope will be born有没有问题 the experts were now fully convinced that the animal was a puma,but where had it come from?As no pumas had been reported missing form any zoo in the countrybut where had it come from?这里的had为什么要用过去完成时呢 ,而且come from这 看看这句语法 时态有没有问题When the prey had discovered the puma,it had been already attacked by t改为 When the prey discovered the puma,it had been already attacked by the puma.呢