must be和must have be有什么区别

　　must be和must have be的区别主要是：must have been表示对过去情况作推测；must be表示所对现在情况的推测。例如：
　　1、He must be ill.
　　他一定是病了。（指现在有病）
　　2、He must have been ill.
　　他当时一定是有病 / 他一定生过病。（指过去有病）
　　3、He must be very rich.
　　他一定非常富有。（指现在有钱）
　　4、He must have been very rich.
　　他当时一定非常富有 / 他一定曾经富有过。（指过去富有过）

简单地说：对过去情况作推测,用must have been；所对现在情况作推测,用must be.
比较：
He must be ill. 他一定是病了.（指现在有病）
He must have been ill. 他当时一定是有病 / 他一定生过病.（指过去有病）
He must be very rich. 他一定非常富有.（指现在有钱）
He must have been very rich. 他当时一定非常富有 / 他一定曾经富有过.（指过去富有过）
下面是几个must have been的例子,有一定的背景或语境,你可以体会一下：
She must have been very young when she got married. 她结婚时一定很年轻.
I didn't hear the phone. I must have been asleep. 我没有听到电话铃,我一定是睡着了.
When you got lost in the forest you must have been very frightened. 当你在森林里迷路的时候,你一定很害怕吧.
I must have been blind not to realize the danger we were in. 我一定是瞎了眼,连我们身临险境也看不出来.
这下你明白must be与must have been 的区别了吗?该不会再误用must have been与must be了吧!

希望能帮到你！

是must be和must have done
must be是必须做某事，must have done说法是错误的,只有can have done过去可能做某事

第二个应该是 must have been