She mustn't see the film,must she?

She mustn't see the film,must she?
她不该看这部电影,她该嘛?
must she?就是 “她该嘛?”
又如：
He can't come today,can he?
他今天不能来吧,能吗?
can he?就等于 “能吗?”
等于在提出自己的问题了以后（如：He can't come today）,又对自己的判断置疑了一下（can he）.