Mr.Brown is supposed to have left for Ltaly last month这里为什么用 have 不用has?

问题描述:

Mr.Brown is supposed to have left for Ltaly last month
这里为什么用 have 不用has?

to后面得接动词的原型,to do,所以得接has

be supposed to do sth
而且to要么就是做介词 要么就是成立一个动词不定式
我没见过to后面还有用第三人称单数的

be supposed to do 用动词原形,所以是have

To 不定式,后加动词的原型
是语法知识