19. by accident 偶然地，意外地

= by chanceI found it by accident. 我很意外地发现了它。

20. on the contrary 与此相反，正相反

It doesn’t seem ugly to me; on the contrary, I think it’s rather beautiful. 我觉得它并不丑，恰恰相反，我觉得它挺美的。

21. I wonder if you… “不知你是否……”

(表示委婉的请求，用于较正式的场合)

I wonder if you would like to come to my birthday party. 不知你是否愿意来参加我的生日聚会。

22. mind doing sth. 介意做某事

I don’t mind sharing a room with him. 我不介意与他合住一个房间。

mind

one

one’s

doing sth.

23.

“介意某人做某事”

I don’t mind him (或his) coming. 我不反对他来。

24. be doing… when…

“正在做……这时……”

be about to do… when…

“正要做……这时……”