阅读理解There have been many different number systems in the wor

阅读理解
There have been many different number systems in the world.A long time ago the Babylonians counted in 60s and today computer count in 2s using only 1 and 0.We call this this 2-number system the binary system.Most systems ,however,count in 10s.This is because we have 10 fingers.We call this system the decimal system from"decem",the Latin word for 10.
The Romans used letters like I,V,X and C to count in 10s but these are not not very easy to use.The numbers most people use today come from India.We think they were invented by the Hindu people there.In the Hindu system the place of each number is important.For example,832 is a different number to 238 or 382.The Hindu system was also used by the Arabs,and we mow call them Arabic numbers,In about the 12th century an Italian called Leonardo Fibonacci wrote a book about Arabic numbers,and people all over Europe began using these numbers.
We do not know who invented the decimal point,but we know that in 1595 a man called Simon Stevin wrote a book about the decimal point.We had to use fractions like 1/2and 3/4 when we talked about numbers smaller than I.
( )1.The article talks about___
A.computer B.Roman numbers C.number systems D.decimal frations
( )2.Computers use a __system of counting.
A.decimal B.60-number C.Babylonian D.binary
( )3.Many people count in 10s because they have ___
A.computers B.2 hands C.10 fingers D.a decimal system
( )4.The Roman system of counting was used in Europe until___
A.about the 12th century B.decimals were invented C.1585 D.Simon Stevin wrote his book
( )5.Numbers smaller than 1 are called___
A.Roman numbers B.fractions C.fingers D.binary numbers
每个题目的原因最好在原文中划出，

1.C（There have been many different number systems in the world.世界上有许多不同的数字系统）
2.D（and today computer count in 2s using only 1 and 0.We call this this 2-number system the binary system）
3.C（Most systems ,however,count in 10s.This is because we have 10 fingers）
4.A（In about the 12th century an Italian called Leonardo Fibonacci wrote a book about Arabic numbers,and people all over Europe began using these numbers.）
5.B（We had to use fractions like 1/2and 3/4 when we talked about numbers smaller than I.
）