Тогда поехали:)
1 ...am I not?
2 ...isn't he?
3 ...aren't we?
4 ...wasn't he?
5 ...were they?
6 ...haven't we?
7 ...hasn't he?
8 ...must he?
9 ...can't we?
10 ...could she?
11 ...may he?
12 ...mightn't they?
13 ...shan't we?
14 ...won't he?
15 ...should I?
16 ...wouldn't he?
17 ...oughtn't you?
18 ...needn't they?
19 ...don't we?
20 ...doesn't he?
21 ...did (не вижу окончание, местоимение вставьте сами)