He ____ not be in the room.I saw him on the playground just now. 用情态动词填空,
问题描述：
He ____ not be in the room.I saw him on the playground just now. 用情态动词填空,
答
He could not be in the room.I saw him on the playground just now.
他不可能在房间里，我刚刚在操场上看见他。
答
用can 表示不可能,这个是比较确定的,因为他在操场上就不可能在屋子里了.
而这是过去时态,后面用的是saw可以看出.
所以用could,是can 的过去时态.