can be表示推测时的用法
问题描述：
can be表示推测时的用法
答
can 或者can be 表示推测时,一般只用于疑问句和否定句,如：
Can he be Mr Green?
He can't be in the room now.
Can /Could it be true?
肯定的推测用must或must be
He must be in the room now.