51.（常考）
remember/forget to do sth 记得/忘记做某事
remember/forget doing sth 记得/忘记做过某事
52. see sb do sth 看见某人做某事（结果）
see sb doing sth 看见某人正在做某事（正在进行中）
be seen to do sth 做某事被看见
53. something to eat/drink 一些吃/喝的东西（词不定式放在something等后修饰这些词）
I need something to eat. 我要一些吃的东西。
54. spend some time (in)doing sth /on sth 花费时间做某事（注意动词要用ing形式）（常考）
spend some money on sth/doing sth 买……花了多少钱
55. Sth is hard/difficult/easy to do . 做好某事很难/容易
56. stop to do sth 停下来去某事（两件事）（常考）
stop doing sth 停止做某事 （一件事）（常考）
stop sb (from) doing sth 阻止某人做某事（常考）
57. take turns to do sth 轮流做……
58. tell sb (not) to do sth 叫某人去（不要）做某事
be told to do sth 被告知不要做某事
59. There is no need (for sb) to do sth 对某人来说没必要做某事
60. There is no time (for sb ) to do sth
have no time to do sth 没时间做某事