Something must be done to stop pollution, isn’t it?
4.当陈述部分的主语是指示代词this, that或these, those时，附加疑问句中的主语分别用it和they。如：
This is important, isn’t it?
That isn’t correct, is it?
These are your friends Tom and Jack, aren’t they?
5.如果陈述部分是以代词one作主语，附加疑问句中的主语在正式场合用one，非正式场合用you,在美国英语中，在非正式场合还可以用he。如：
One can’t be too careful, can one?或can you?
One should do his duty, shouldn’t he?
6．如果陈述部分用I’m 结构，附加疑问部分一般用aren’t I。如：
I am strong and healthy aren’t I。
7．当陈述句为there be结构时，附加疑问句中的主语也用there。如：
There’s no help for it, is there?
There’s something wrong, isn’t there?
8．陈述部分带有seldom, hardly, never, rarely, few, little,nowhere, nothing等否定词或半否定词时，附加疑问部分的动词用肯定形式。如：
Bob rarely got drunk, did he?
Few people know him, do they?
She seldom goes to the cinema, does she?
如果陈述部分的否定词带有否定前缀，那么，该陈述部分作肯定处理，附加疑问部分一般仍用否定形式。如：
He was unsuccessful, wasn’t he?
Tom dislikes the book, doesn’t he?
9．当陈述部分为主从复合句时，附加疑问部分一般应与主句的主语和谓语动词保持对应关系。如：
She says that I did it, doesn’t she?
I told them not everybody could do it ,didn’t I?
但当陈述部分的主语是I，谓语是think, believe, suppose, expect这类动词时，附加疑问部分则往往与从句中的主语和谓语动词保持对应关系，但要注意否定的转移。
I suppose that he’s serious isn’t he?
I don’t think she cares, does she?
10．当陈述部分是并列句，附加疑问句则需和就近的分句的主语和谓语一致。如：
Xiao Lin has been writing letters all afternoon but he should finish them now,
shouldn’t he?
11．在由“祈使句+附加疑问”构成的附加疑问句中，附加疑问部分一般用will you, won’t you, would you,有时也可用can you, can’t you, why don’t you, could you等。如：
Don’t open the door, will you?
Give me some cigarettes, can you?
Take a rest, why don’t you?
但是，以let’s开头的祈使句，附加疑问部分用shall we;以let us开头的祈使句，如果含义是allow us，不包括听话人在内，疑问部分用will you。如：
Let’s have a basketball match this afternoon, shall we?