【俚语】

Sit on (one's) hands 置之不理

【例句】

When we needed help from Mary, she just sat on her hands.
当我们需要Mary帮助的时候，她竟然置之不理。

(one's) hands are tied 受到限制

【例句】

I'm sorry. There's nothing I can do. My hands are tied.
对不起，我什么都做不了，我也受到限制。

Know sth. like the back of your hand
了如指掌

【例句】

You should ask Samantha for directions—she knows this city like the back of her hand.
问路你要找Samantha啊——她对这座城市了如指掌。

Live hand to mouth 勉强度日

【例句】

He has a wife and two children and they live from hand to mouth on what he earns.
他有老婆和两个孩子，依靠他的收入勉强度日。

Win sth. hands down 轻松取胜

【例句】

They are a strong team and they expect to win the game hands down.
他们是一支强队，他们有望轻而易举地赢得比赛。