阅读下面短文, 请根据短文后的要求进行答题。（请注意问题后的词数要求）
[1] The year 2008 has one extra day in it--February 29th, why does this happen? Well, it actually takes the planet Earth a little more than 365 days to revolve completely around the sun. After four years an extra 24 hours have accumulated so an extra day is added to the calendar.
[2] It is called a leap year because hundreds of years ago in England, the extra day wasn't legally recognized. The British just leapt over that day. Therefore a year with 29 days in February is consequently called a leap year and that                         . If you are born on 29th February in a leap year, there are difficulties in celebrating your birthday. So people tend to celebrate on either 28th February or 1st March every year.
[3] There is a well-known tradition in the UK associated with 29^th February, introduced many centuries ago. Women are allowed to break with tradition and propose (求婚) to their boyfriends on this day. This all started back in the 5th Century, when a famous Irish saint, Bridget, complained to Saint Patrick, another famous Irish saint, that women had to wait too long for men to propose. According to the legend, Saint Patrick said any female longing for a proposal could ask their boyfriend to marry them on this additional day in February.
[4] Now in 2008, there are calls for 29th February to become a public holiday. Some people believe that it should be an official day off, because no one gets paid for working in a leap day. For the moment though, the British still have to go to work on this day.
What is the main idea of the text? ( no more than 8 words)
                                                                                          
Complete the following statement with proper words. ( no more than 5 words)
Hundreds of years ago, a popular tradition in England was recommended
Which                       29th February.
How long does it take the planet Earth to revolve completely around the sun? (no more than 9 words)
                                                                                                
Fill in the blank in Paragraph 2 with proper words. ( no more than 8 words)
                                                                                         
What does the word  "them" (Line 5, Paragraph 3) probably refer to? ( no more than 3 words)