gain by的用法和樣例：
例句
- That silly woman gushes over every new actress that she meets, telling each one how wonderful she is; I don't know what she hopes to gain by it, except perhaps some rather false gratitude.
那個(gè)蠢女人碰見(jiàn)每個(gè)新女演員都胡亂吹捧一番，把每一個(gè)都說(shuō)成是如何了不起，我不了解她想借此得到什么東西，可能不過(guò)得到一些假惺惺的感激而已。 - You can gain by watching how she works.
看她怎樣工作就可獲益。
