1　Be in the air 将要发生的事情

The feeling or idea that something new is about to happen or is going to change.
Example: From the arguments going on at the meeting, it seems that a change in policy is in the air.

2 Clear the air 消除误会

To settle a dispute and restore good relations
Example: We had a meeting with the workers, and I think we’ve cleared the air now.

3　Cost an arm and a leg 极其昂贵

To be very expensive
Example: I love that fur coat. However, I don’t think I’m going to buy it because it costs an arm and a leg.

4　A bad egg 缺乏道德的人

Somebody who has no moral principles and should be avoided
Example: You mustn’t lend Tim money, he’s a bad egg. You’ll never see him or your money again!

5　In the Bag 稳操胜券

Said of an achievement which is secure
Example: We have the deal in the bag. The client came in this morning to sign the agreement.