a friend of his的用法和样例：
- John send a parcel to a friend of his.
- He regards me as a friend of his all the time.
- A friend of his happened to be sitting in a railroad-coach next to a young man who was obviously depressed.
- A friend of his, a repairman who knew the condition of the car, kept urging him to trade his old car for a new model.
- I would like you to meet a friend of mine.