The bagpack must be Linda's,isn't it?
must表示推测时,反意问句不用must了,也不用can,就用前句的谓语和主语
（根据时态人称决定）
He must have left,hasn't he?
He must have left yesterday,didn't he?
注意时态的不同.
The bagpack must be Linda's,isn't it?
must表示推测时,反意问句不用must了,也不用can,就用前句的谓语和主语
（根据时态人称决定）
He must have left,hasn't he?
He must have left yesterday,didn't he?
注意时态的不同.