Explanation:

- Sweety has been walking on air since her painting won first prize.

- This means she is extremely happy or elated.

- Answer

- Walking on eggshells

- Refers to being very cautious or careful to avoid upsetting someone.

- Waiting in the wings

- This means being ready to take action or step in when needed, often in a supportive role.

- Walking into the lion's den

- Refers to entering a situation that is risky or dangerous.