Question

Today, February twenty-ninth, is leap day. This date only appears on the calendar once every four years. But why?

Everyone knows the Earth takes three hundred sixty-five days to travel around the sun. Well, that is not exactly correct. The Earth really takes three hundred sixty-five days, five hours, forty-eight minutes and forty-six seconds to complete its orbit around the sun.

The problem for people developing calendars (日历) was what to do with the extra(额外的) five hours, forty-eight minutes and forty-six seconds.

People needed calendars to help them know when to plant crops and when to celebrate religious holidays. The ancient Greeks and Chinese had a solution(解决办法). They produced calendars that included extra months every nineteen years.

The ancient Romans had a different solution. In the year forty-six, the Roman ruler Julius Caesar made a new calendar. The Julian calendar included an extra day every four years. But there was a problem. The Julian year was just over eleven minutes longer than the cycle(循环) of the seasons. In fifteen eighty-two, Pope Gregory the Thirteenth established a new calendar to keep a better recorder of the days. Pole Gregory was the religious leader of most of Europe. He decided that years that could be divided by four would add a day. However, years that ended in two zeros and that could not be evenly(均匀地) divided by four hundred would not be leap years. For example, the years seventeen hundred, eighteen hundred and nineteen hundred were not leap years. But the years sixteen hundred and two thousand were leap years

So leap years are years with three hundred sixty-six days, instead of the usual three hundred sixty-five. This extra day is added to the calendar on February twenty-ninth, sometimes known as leap day. People born on leap day may be called “leaplings.” They usually celebrate their birthday on February twenty-eight or March first. 

Title:     71    

Reasons	The Earth really takes 365 days, 5 hours, 48 minutes and 46 seconds to complete its orbit around the sun
	72     is needed to benefit people’s daily life and work
73	How to deal with the extra 5 hours, 48 minutes and 46 seconds
74	75	Ways
	Ancient Greeks and Chinese	Producing   76    every 19 years
	77	Producing an extra day      78
	The Pope Gregory	Producing a leap day if the year could be divided      79     . No leap day when the year ended in two zeros but could not be divided by 400
Result	Leap day was accepted and February twenty-ninth      80     to the calendar

Answer 1

71. Leap Day/ An Extra Day    72. A calendar    73. Problem    74. Solutions 

 75. People  76. extra months    77. Julius Caesar    78. every four years  

 79. by four     80. was added