about four years old的用法和样例：
- Alice is a little girl,about four years old.
- My own memories begin in the town of Bauru in the state of Sao Paulo when I was about four years old.
- The dog has been x-rayed and is believed to have been about four years old when it died.
- They began the club about four years ago.
- Although he is only four years old, he is able to tell time.