Question

2. I think she must be our new teacher, _______?

2. I think she must be our new teacher, _______?
A. don’t I B. doesn’t she
C. mustn’t she D. isn’t she 为什么答案一定是D ，，，，B 为什么不对

Answer 1

你好。
1 首先，must在这里是表猜测的，解释为“肯定，一定”，不解释为“必须”。
2 再看看 she must be our new teacher的原始句子： she must be our new teacher== I am sure she is our new teacher.
3 这样一来 I am sure 是插入语成分，你可以忽略掉，she is our new teacher的反意疑问句结构是：she is our new teacher，isn't she?
4 再回到你的句子 I think she must be our new teacher, ISN'T SHE ?--------- i think是插入语成分，你可以忽略掉. 这些刚才讲的就构成了反意疑问句结构。

Answer 2

情态动词表示推测时，反意问句不能用这一情态动词。而是把句子变为一个无情态动词的句子，再根据这个句子来变反意问句，如 she must be our new teacher=she is our new teacher,所以反意问句为isn't she?

Answer 3

反义问句对应的是 宾语从句内容。
也就是SHE 的情况，而,不反问情态动词，这是普遍规律

Answer 4

i think比较特殊，否定疑问是从句部分。我简单点说吧，你不考虑这里是不是must，就句子是she is our teacher 还是she does our teacher这样比较好理解为什么选d了。

Answer 5

D对，must情太动词这里有表猜测，比较肯定的猜测，真正对应的动词是be 所以D对