Aren't you going to the aerobics class this morning?
今天上午你不是去上有氧运动课吗?
I asked him to fix it for me, but he wouldn't.
我请他帮我修理,但是他不肯。
Twenty or thirty pages of information handed to any of the major world powers around the year 1925 would have been sufficient to change the course of world history.