1, i'm sorry to bother you while you're working but i................ask you a question(can/had to/must/may)
2,we..............ensure the telegram arrives in time (had to/mustn't /'d rather/might)
3,he.................keep his family because his wages were too low(couldn't/mustn't /can't/didn't have to)
4,...........make an appointment to see the doctor?(may i/could i/will i/shall i)
5,i ...................go swimming then i young(could/would/used to/both b&c)
6,................take this letter to the post office,please?(may you/must you/would you/X)
7,in our family mu father........................sit at the top of the table(used to/had to/ought to/must)
8,i................swim in this water:it is much too cold(mightn't/mustn't/can't/don't have to)
9,you..........imagine my surprise when i heard the news(can/ought to/will/all of these)
10,you................do some work instead of sitting there reading the paper(would rather/ought to/won't/don't have to)
11,be careful how you hold that jug it.............break easily(may/ought to/will/might)
12,i am not sure where to go for my holiday,but i......................go to china(should/may/have to/needn't)
13,we hag free tickets,so we.................pay to get into the concert(didn't have to/couldn't/mustn't/shouldn't)
14,shall i clean the window today?no you.....................(mustn't/needn't/on't have/shouldn't
15,you have been traveling all day.you......................a walk now(could take/can't take/can take/my take
=>
1. may
2. had to
3. couldn't
4. may I
5. used to
6. May you
7. used to
8. mustn't/ can't
9. can
10. ought to
11. might
12. may
13. didn't have to
14. needn't
15. can't take