题目内容：

A:I can’t find my bag.Have you seen it?
B:No.You _______________________________________(一定是把它放在) behind the door.
I must have put it 如果把must

优质解答

must表肯定的猜测,去掉Must变成陈述事实,这里B是在做猜测,他并不知道实际上在哪,所以不能删