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.
那個蠢女人碰見每個新女演員都胡亂吹捧一番，把每一個都說成是如何了不起，我不了解她想藉此得到什麼東西，可能不過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。
