smile/grin from ear to ear 笑得合不拢嘴

He smiled from ear to ear when he received this birthday gift.

当他收到这生日礼物时笑得合不拢嘴。

talk one’s ear off 喋喋不休

I’m sorry to talk your ear off, i just need somebody to talk to.

不好意思，对妳说了这么久，我只是想找一个人倾诉。

play it by ear见机行事

He can play it by ear and handles everything in order.

他能随机应变，所以他把一切事物处理的井井有条。

keep an ear to the ground 保持高度警觉，及早发现那些即将发生的事情的预兆

Reporters keep an ear to the ground so as to know as soon as possible what will happen.

记者们注意舆论的动向，以便尽早知道将要发生的事情。