Is that Tom under the tree?--------It_____be Tom .Tom is on holiday inBeijing now.是can't 还是mustn't
问题描述：
Is that Tom under the tree?--------It_____be Tom .Tom is on holiday in
Beijing now.
是can't 还是mustn't
答
can't
can't be 表示一定不是---
后面有一句，汤姆现人在在北京度假呢
答
isn't吧
答
can't
答
can't
情态动词对现在表推测
O(∩_∩)O~
答
can't
问：树下的那个人是汤姆吗?
答：不可能是汤姆,汤姆正在北京度假呢.
此处应填否定回答 can't be
答
can't
否定猜测只能用can't