Here are the phrases matched with their definitions:

1. **give sb a hint** - give a small indication or suggestion to help someone find an answer or a solution
2. **cross my mind** - suddenly think of something / come into your mind
3. **have a thought** - think of something, often suddenly or unexpectedly
4. **have second thoughts** - change your opinion
5. **make up my mind** - make a decision
6. **lose concentration** - stop paying attention
7. **use your imagination** - to form a picture of something or someone in your mind

1Give sb a hint:
2Cross my mind
3Have a thought:
4Have second thoughts:
5Make up my mind:
6Lose concentration
7Use your imagination