A：Professor, I've handed in my paper. Did you read it?教授，我的论文已经交了。你看了吗?
B：Yes. You've done a good job. But there's one thing. You should narrow down your topic.是的。你写得不错。但是有一个问题。你应该缩小你的话题。
A：What about water pollution instead of pollution?用“水污染”代替“污染”怎么样?
B：Well done!非常好!