51. The horse won’t be well enough (run) to run in tomorrow’s race. He doesn’t seem (have) to have recovered from his long journey. ( enough to V , seem to V )

52. At first I enjoyed (listen) listening to him but after a while I got tired of (hear) to hear the same story again and again.

53. It is usually easier (learn) to learn  a subject by (read) reading books than by (listen) listening to lectures. ( It is easy to do something: thật dễ dàng để làm một việc gì đó , Sau by + V - ing )

54. It wouldn’t be safe (start) to start down now; we will have (wait) to wait till the mist clears. (  "be safe to V": an toàn để làm gì.,  "have to V": phải làm gì. )

55. After (discuss) discussing  the matter for an hour the committee adjourned without (have) having  reached any decision.

56. It’s not much use (have) a bike if you don’t know how (use) to use it. ( How to V )

57. I distinctly remember (pay) paying him. I gave him 2$. ( remember Ving )

58. Did you remember (give) giving him the key of the safe? - No, I didn’t. I will go and do it now. (  remember Ving )

59. Please forgive me for (interrupt) interruptin you but would you mind (repeat) repeating that last sentence.

60. He made a lot of money by (buy) buying tickets in advance and (sell)  selling them twice the price on the day of the match.

Cho mìn xin ctlhn nha!

@Bảo Ngọc