1. Leap year recurs every four years, and in that year February has 29 days .
    每四年闰年一次，而那一年中，二月有29天。

2. Look before you leap. First think, then act.
    三思而后行。

3. It is: If a year´s number can be divided by 4, it won´t be a leap year if it can be further divided by 100.
    这就是：如果某一年的数字被4除尽后还能被100除，那么这一年就不是闰年。