【俚語】

Sit on (one's) hands 置之不理

【例句】

When we needed help from Mary, she just sat on her hands.
當我們需要Mary幫助的時候，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.
對不起，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.
問路你要找Samantha啊——她對這座城市了如指掌。

Live hand to mouth 勉強度日

【例句】

He has a wife and two children and they live from hand to mouth on what he earns.
他有老婆和兩個孩子，依靠他的收入勉強度日。

Win sth. hands down 輕松取勝

【例句】

They are a strong team and they expect to win the game hands down.
他們是一支強隊，他們有望輕而易舉地贏得比賽。