Choose the correct idiom to be used in each of the situations below.
to keep a civil tongue
to keep a straight face
to keep something under wraps
to keep someone on tenterhooks
to keep one’s fingers crossed

Situation 1.
- When does your sister take the exam?
- In two days.
- Tell her I wish her good luck.

Situation 2.
- Have you heard about their engagement?
- What engagement?
- Oh, they still keep it a secret, don’t they?

Situation 3.
- Sue, please, tell me what makes you so unhappy. Don’t keep me in suspense, please!

Situation 4.
The boy is so rude. Everybody will turn away from him if he doesn’t speak decently.

Situation 5.
- I knew it was Jack who played the trick. He couldn’t keep his face from laughter.