What are 4 idoms?

Here are four idioms:

1. Break the ice – to initiate conversation in a social setting to relieve tension.
2. Bite the bullet – to face a difficult or unpleasant situation with courage.
3. Burn the midnight oil – to work late into the night, usually on a project or task.
4. Let the cat out of the bag – to reveal a secret or disclose information unintentionally.