a painter's brush的用法和样例：
- We should brush our teeth at least twice a day.
- Our advanced troops had a brush with the enemy this morning.
- The motorcyclist had a brush with danger as he skidded round the bend.
- There is a vein of melancholy in his character.
- There was a long lag in forwarding mail to us.
- A bowl of hot chicken soup is good for you.