Gerund and To-infinitive
1. If a thing is not worth(do) at all, it is worth(do) well.
2. I'm beginning (understand) what you mean.
3. The boys like (play) games but hate (do) exercises.
4, I can't understand her (behave)like that.
5. It wouldn't be safe (start) down now, we'll have (wait)till the mist clears.
6. I tried ( explain) to him but he refused (listen) and went on (grumble)
7. She likes her children (go) to the dentist every 6 months.
8. I know my hair wants (cut) but I never have time (go) to the hairdresser's.
9.-Why didn't you drink it?

-] didn't like (drink) it as I didn't know what it was .
10. Did you advise him (go)to the police?

-No, I didn't like (give) any advice on such a difficult matter.
11. 1 (like) (bathe)there but there wasn't time.
12. Do stop (talk); I'm trying (finish) a letter.
13. It is usually easier (learn) a subject by (read) books than by (listen) to lectures.
14. Some people seem ( have) a passion for (write) to the newspapers.
15. I resented (bve) unjustly accused and asked him (apologise).
16. He made me (repeat) his instructions (make) sure that I understood what I was
(do) after he had gone.
17.1 keep (try) (make) mayonnaise but I never succeed.

-Try (add)the yolk of a hard-boiled egg.
18. I distinctly remember (pay) him. I gave him $2.
19. It's no good (write) to him. He never answers.
20. I knew I was not the first (arrive), for I saw smoke ( rise) from the chimney.
21. I remember (read) a review of that book and think I (like) (get) it.
22. I hate (borrow) money.
23. I (like) (photograph)it but I had no more film.
24. I (like) (ask) a questionbut I was sitting so far back that I'd be heard.
25. I can remember (be) in hospital when I was 4.
25. This book tells you how (win)at games without actually (cheat).
26. The boys next door used (like) (make) and (fly) model aeroplanes, but they
seem (stop) (do) that now.
27. Don't forget (post) the letter I gave you.
28. There was a lot of traffic but we managed (get) to the airport in time.
29. When I'm tired ,I enjoy (watch) TV. It's relaxing.
30. It was a nice day, so we decided (go) for a walk.
31. It's a nice day;Does anyone fancy (go) for a walk?
32. I'm not in a hurry. I don't mind (wait).
33. They don't have much money. They can't afford (go) out very often.
34. I wish that dog would stop (bark). It's driving me mad.
35. Our neighbour threatened (call) the police if we didn't stop the noise.
36. We were hungry, so I suggested (have) dinner early.

Cho tập hợp X={0;1;2;3;4;5;6;7;8;9}, người ta lập 2 tập hợp con của X, tập hợp A={0;1;2;...;n} gồm n+1 số tự nhiên đầu tiên và B={n+1;n+2;...;2n}. Từ mỗi tập hợp A và B đó, người ta lập số tự nhiên có 5 chữ số đôi một khác nhau, trong số đó có hai chữ số hàng chục nghìn và hàng nghìn được viết bởi các chữ số lấy trong tập hợp A, 3 chữ số còn lại được lấy trong tập hợp B. Hỏi lập được bao nhiêu số tự nhiên như vậy và số lớn nhất là bao nhiêu?