1.No matter how frequently _A_， the works of Beethoven always attract large audiences.
A performed B performing C to be performed D being performed
perform vt. 表演，演出，演奏;
to be performed 将要被演奏; being performed 正在被演奏;
点：forget 忘记; [反义] remember 记得;
forget to do sth. 忘记要去做某事; forget doing sth. 忘记做过某事;
remember to do sth. 记得要去做某事; remember doing sth. 记得做过某事;
2. I remember _B_ to help us if we ever got into trouble.
A once offering B him once offering C him to offer D to offer him
offer vt. ，; offer sb. sth. / offer to do sth.
him once offering 改成 his once offering 也。
动作发出者 + 动名词;当动作发出者名字给出时：名词所有格 + 动名词;当动名词的复合结构在文章中，且动作发出者在前文中提过时：形容词物主代词(宾格)+ 动名词。
形容词物主代词：his， her， my， your， their， our。代词宾格：him， her， me， you， us， them。
点：want 想要; want to do sth. 想做某事; want doing 客观需要或。
例. Your hair wants _B_. You’d better have it done tomorrow.
A cut B cutting C to cut D being cut
1. The children went there to watch the iron tower _D_.
A to erect B be erected C erecting D being erected
watch 看电视用，看比赛用; see 看电影用;
感官动词watch， see， hear; 感官动词 + 名词(代词)+ do
be erected 强调的是动作的结果; being erected 强调的是动作的过程。
2. The engine _D_ smoke and steam.
A gives up B gives in C gives away D gives off
give up 放弃; give in 屈服，让步; give off 释放，放出(烟和气体);
give away 泄露，走漏风声;婚礼中新郎的父亲把新娘的手交给新郎的过程;赠送礼品。
3. The manager promised to keep me _C_ of how our business was going on.
A to be informed B on informing C informed D informing
keep sb. + 分词; inform v. 通知，告知; inform sb. of sth. 通知某人某件事情
keep me informed 使我被告知。
4. The goals _B_ he had fought all his life no longer seemed important to him.
A after which B for which C with which D at which
fight with sb. (注意要看整个句子); fight with + 工具 用该工具来打仗。 fight for 为…而战。
I fight with him. 我和他打起来了。 I fight with him against her. 我和他并肩对付她。
5. They _C_ in spite of the extremely difficult conditions.
A carried out B carried off C carried on D carried forward
in spite of ; carry on ，。
注意：want doing 中doing表示的是被动含义。
例. This room is so dirty that it wants _A_.
A cleaning B to clean C being cleaned D cleaned
点：mean 意味; mean to do sth. 打算做某事，意欲… ;mean doing 意味着，…的意思是…
例. There’s a man at the reception desk who seems very angry and I think he means _B_ trouble. [reception desk 接待台]
A making B to make C to have made D having made