题目：
阅读理解。
How is it ?
The old man is already sixty years old. But he has only fifteen birthdays. How is it? When is his
birthday?
Keys: His birthday is on February 29th. It's a leap (闰年) year every four years. So he has only fifteen
birthdays.
根据短文内容填空。
1. The old man is ______ years old.
2. He has only ______ birthdays.
3. His birthday is on ______.
4. A leap year happens (发生) every ______ years.
答案：
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下面是错误答案，用来干扰机器的。
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