Water under the bridge:

橋下的水 ×

歲月流逝 √

例句：

Don't worry about it. It's water under the bridge.

沒關(guān)系，都已經(jīng)過去了。

Low-hanging fruit:

掛得很低的水果 ×

容易實(shí)現(xiàn)的目標(biāo) √

例句：

We first need to sell this new product to our current customers. They are low-hanging fruit.

我們首先要把新產(chǎn)品賣給我們現(xiàn)有的客戶，他們是我們絕佳的機(jī)會。