Do you know your mobile phone number well!？Your number has 11 digits （數(shù)字）.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 include three parts.Each part has a different meaning.The first three numbers tell you the mobile phone service provider you are using.For example，135 is for the China Mobile Communication Corporation （中國(guó)移動(dòng)） and 188 is for China Unicom （中國(guó)聯(lián)通）.The fourth to the seventh digits tell you where the number is from.And the last four digits are random.
   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 from 1999.
  Eleven digits can make tens of billions of mobile phone numbers.That's enough for each person to have seven for eight phone numbers to use in China.Also，we can use the mobile phone numbers again.Usually，the service provider will use a canceled number again after three to six months.If you call a number that you haven't called for a long time，you may find 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 make 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）What can we learn from the mobile phone number 188-4792-8343？

B

B

A．The service provider is the China Mobile Communication Corporation.
B．The digits 4792 tell you the area the mobile phone number is from.
C．There are ten digits in the mobile phone number.
D．The digits 8343 tell you the number of service providers in China.
（2）Why do we use 11-digit mobile numbers in China？

A

A

A．There are many people in China.
B．People in China can remember numbers well.
C．11 is a lucky number for Chinese people.
D．It helps people to remember more phone numbers.
（3）What does the underlined word "canceled" mean in Chinese？

B

B

A．新型的.
B．已撤銷的.
C．有用的.
D．特殊的.
（4）

C

C

can make the most mobile phone numbers.
A．10 digits starting with 1
B．11 digits starting with 0
C．11 digits starting with 1
D．10 digits starting with 0
（5）Which countries use phone numbers with 10 digits？

D

D

A．Britain and Japan.
B．Britain and China.
C．Canada and Australia.
D．India and Australia.