---You were brave enough to raise objections at the meeting.

---Well, now I regret ___ that.

A. to do　 B. to be doing　 C.　to have done　 D.　having done

答案：D。regret having done sth. 对已发生的事感到遗憾。regret to do sth. 对将要做的事感到遗憾。本题为对已说的话感到后悔，因此选D。

8.5 cease doing/to do

cease to do 长时间，甚至永远停做某事，cease doing　 短时停止做某事，以后还会接着做。例如：

That department has ceased to exist forever. 那个系已不复存在。

The girls ceased chatting for a moment when their teacher passed by. 姑娘们在老师走过时，停了会聊天。

8.6 try doing/to do

try to do　努力，企图做某事，try doing　试验，试着做某事。例如：

You must try to be more careful. 你可要多加小心。

I tried gardening but didn't succeed. 我试着种果木花卉，但未成功。

8.7 go on doing/to do

go on to do　做了一件事后，接着做另一件事，go on doing　继续做原来做的事。例如：

After he had finished his maths，he went on to do his physics. 做完数学后，他接着去做物理。

Go on doing the other exercise after you have finished this one. 作完这个练习后，接着做其他的练习

8.8 be afraid doing/to do

be afraid to do　不敢，胆怯去做某事，是主观上的原因不去做，意为"怕"，be afraid of doing　担心出现doing的状况、结果。doing 是客观上造成的，意为"生怕，恐怕"。She was afraid to step further in grass because she was afraid of being bitten by a snake.

她生怕被蛇咬着，不敢在草丛中再走一步。

She was afraid to wake her husband. 她不敢去叫醒她丈夫。

She was afraid of waking her husband. 她生怕吵醒她丈夫。

8.9 be interested doing/to do

interested to do　对做某事感兴趣，想了解某事，interested in doing　 对某种想法感兴趣，doing 通常为想法。例如：

I shall be interested to know what happens. 我很想知道发生了什么事。(想了解)

I'm interested in working in Switzerland. Do you have any idea about that?

我对在瑞士工作感兴趣。你想过这事吗? (一种想法)

8.10 mean to doing/to do