A：Professor, I've handed in my paper. Did you read it?教授，我的論文已經(jīng)交了。你看了嗎?
    B：Yes. You've done a good job. But there's one thing. You should narrow down your topic.是的。你寫(xiě)得不錯(cuò)。但是有一個(gè)問(wèn)題。你應(yīng)該縮小你的話題。
    A：What about water pollution instead of pollution?用“水污染”代替“污染”怎么樣?
    B：Well done!非常好!