1. Expression：lift a hand

Explanation：To make the slightest effort to do something, especially to help someone. （尽举手之劳，帮一点点忙）

Example：He didn’t lift a hand to help me when I was in trouble.

我陷入困境时，他一点也不帮忙。

She does all the work in the house. Nobody else lifts a hand.

她在家里做完所有的工作，没有人帮她。

情景对话：

A: Tina, would you like to help me make the apple pies?

Tina，你可以帮我做苹果派吗？

B: Sorry, Mum. But I am watching my favourite TV programs.

对不起，妈妈，我在看我最喜欢的电视节目 。

A: Tina, you are really let me down. You never lift a finger around the house.

Tina，你真的很让我失望，你在家里从来不帮一点忙。

2. Expression：burn one’s fingers

Explanation：To hurt or harm oneself. （因管闲事而吃苦头，伤害到自己，自寻烦恼，自找苦吃）

Example：It was too late for him to regret as he had burned his fingers.

他因管闲事而自找苦吃，真是后悔莫及。

If you invest in that company and you'll burn your fingers. Its future is very uncertain.

如果你投资那家公司会亏本的，因为那家公司前途难卜。

Don't burn your fingers by getting too involved.

不要介入得太深以致于惹火烧身。

I burned my fingers by letting them use my car. They crashed it and the repair cost will be very expensive.

把车借给他们我可吃了大亏——他们把车子撞坏了，修理费要一大笔钱。