题目内容：

    Have you ever counted the number of digits (数字) in your mobile phone number? Your number has 11 digits. You may sometimes find it hard to remember your number. That’s because China has the longest mobile phone numbers in the world. Why is that?

The 11 digits can be divided into three parts. Each pare has a different meaning. The first three numbers tell you which mobile phone service provider you are using. For example,135 is for the China Mobile Communications Corporation ( 中 国 移 动 ) and 188 is for China Unicom ( 中 国 联 通 ). The fourth to the seventh digits tell you which region the number is registered (注册) in. And the last four digits are random (随机的).

The main reason for using 11 digits is that we have the largest population in the world. We once had 10 numbers. But as our population grew, there were not enough numbers for us to use. So we began to use 11 digits starting from 1999.

Eleven digits can be used to make tens of billions of mobile phone numbers, according to the Xinhua News Agency. That’s enough for each person to have seven or eight phone numbers to use in China.

Plus, mobile phone numbers can be recycled. Usually, the service provider will reuse a canceled number after three to six months. If you call a number that you haven’t contacted for a long time, you may find that its owner has changed.

Besides China, Britain and Japan also use 11-digit  mobile phone numbers. But their numbers always start with 0. So they cannot create as many numbers as we can. Countries like  the United  States,  Australia  and India  use phone numbers  with 10 digits.  Canada’s mobile phone numbers are perhaps the world’s shortest: they use seven digits.

1.Which country has the longest mobile phone numbers in the world?

 ____________________________does.

2.What can we know from the first three digits of a phone number?

The first three digits stand for_____________________.

3.Why does China use 11 digits for phone numbers?

Because___________________________.

4.When can a phone number be recycled?

The service provider will ___________________________.

5.Do Canadians have the world’s shortest mobile phone numbers?

___________________________________________.