The Indians invented and developed the system of numbers from 1 to 9 and 0. We can use the ten numbers to make any number from the biggest to the smallest.

　 However, the ancient Romans invented a different system (系统) of numbers. They used symbols (符号) and replaced them. 1 is “Ⅰ” and 2 is “Ⅱ”. For larger numbers, they invented new symbols—5 is “Ⅴ”, 10 is “Ⅹ”, and so on. But they didn’t have a symbol for zero.

　 Here’s a table of the Roman numbers.

　 The Romans combined their symbols. In this way, “Ⅶ” means “5+1+1”, or 7. However, they found that “ⅡⅡ” (for 4) and “ⅤⅡⅡ” (for 9) were too confusing, so they thought out another idea.

　 If the “Ⅰ” comes after the “Ⅴ”, then you add it (Ⅵ is 6); if the “Ⅰ” comes before the “Ⅴ”, then you subtract (减去) it (Ⅳ is 4). The rule is that you are allowed to add up to three (e.g. Ⅷ is 8), but only subtract one (e.g. XL is 40).

　 How to remember the symbols?

　 Ⅰis like a finger. In a whole hand, the thumb (拇指) and the little finger make a V. Ten fingers are both hands, so the two Vs make an X..

　 Here is a way to remember the other symbols (L, C, D, M)：Little Cats Drink Milk.

(　 ) 51. How many numbers can we make according to the Indians’ system ?

　　　　 A. three: 0, 9, 1　　 B. ten　　　　　 C. eleven　　　 D. lots of

(　 ) 52. Which number was not in the ancient Roman’s number system?

　　　　 A. 1　　　　　　 B. 9　　　　　 C. 0　　　　　　 D. 5

(　 ) 53. What does the underlined word “combined” probably mean in the passage?

　　　　 A. 合并　　　　 B. 分离　　　　 C. 增加　　　　 D. 削减

(　 ) 54. What does MD mean according to the Romans’ rule of calculating?

　　　　 A. 500　　　　　 B. 1000　　　　 C. 1500　　　　 D. 2000

(　 ) 55 Which sentence is NOT true according to the passage?

　　　　 A. “Little Cats Drink Milk” can help us to remember some of the numbers symbols.

　　　　 B. The Indians invented the system of numbers from 1 to 9 and 0.

　　　　 C. You are not allowed to make a number like “XXL”

　　　　 D. The ancient Romans repeated symbols to make any number.

Always forgetting your long passwords(密码)? Worried about being hacked(被攻击)?All these worries will soon become history. Scientists have found that upper-casing(大写)your password can help you reduce the chance being hacked.

Usually passwords are six letters or more.However,50 percent of people choose a common word or simple key combination for their password. The most used passwords are 123456, abcdef and abc123. In fact, if your passwords are in lower-case(小写),it will be easily hacked by a hacker. According to a study, it only takes a hacker ten minutes to hack a six-letter password which is in lower-case, but if you make the letter in upper-case, it can take up to ten hours. So if you want to make your account much safer, you should make your password upper-case. Of course, you can also add numbers or symbols to your password. Most of the time a hacker’s computer has to work for 18 days to break a password, but if you choose a nine-letter password that includes numbers and symbols, it can take a hacher’s  computer 44,530 years to break it.

1.Scientists have found that   your password is much safer for  

your account.

2.According to the passage,______is not one of the most used

passwords.

3.It takes a hacker___to hack a six-letter password which is in

lower—case.

4.The Chinese meaning of the underlined word is       

A.数字     B.符号      C.色彩       调料

5.What is the main idea of the passage?

Did you notice the number on the book in a library? That number is part of the system used by libraries to organize their collections of books. And it’s used in many countries. The number on each book tells you exactly what kind of book it is. This system is also useful for knowing where to go in the library to find a book.

In this system, there are ten large groups of books. Each of these groups has its own number, such as 100, 200, etc. So, for example, any books about language will have a number 400. On the other hand, any books about history will have a number 900. So, a number in the hundreds place tells you what general group a book is in. If you find a book that has a number in the 500s, you know it is a book about science.

However, science is a big group, so the tens place is used to make a more detailed set of science books. For example, math books are included in the group of science books. Math books all have numbers between 510 and 519. Books about the history of Africa have numbers between 960 and 969.

The system uses the ones place to give a more exact limit for the subject of a book. A book on the history of South Africa will have the number 968.

As you can see, it is a simple system to use as long as you understand what the numbers mean. With this system, the library can keep its books well organized, and people can easily find the book that they want.

1.The reading is about       .

   A. libraries

B. working in a library

   C. how numbers are organized

D. how books are organized in libraries

2.The number system is NOT used to       .

   A. find where a book is 

B. tell you the title of a book

   C. tell you what kind of book a book is        

D. organize the collections of books in libraries

3.According to the reading, which sentence is TRUE?

   A. The number on a book can’t be bigger than 900.

   B. There are ten big groups for books in this system.

   C. History books can have any number between 500 and 900.

   D. This system uses both numbers and letters for some books.

4.A book about math can be found in the same group of books as       .

   A. reference books   B. school books     C. science books   D. art books

5.Which two numbers would indicate a book about language and a book about science?

   A. 439 and 493       B. 439 and 568      C. 530 and 560     D. 563 and 436

Always forgetting your long passwords(密码)? Worried about being hacked(被攻击)?All these worries will soon become history. Scientists have found that upper-casing(大写)your password can help you reduce the chance being hacked.
Usually passwords are six letters or more.However,50 percent of people choose a common word or simple key combination for their password. The most used passwords are 123456, abcdef and abc123. In fact, if your passwords are in lower-case(小写),it will be easily hacked by a hacker. According to a study, it only takes a hacker ten minutes to hack a six-letter password which is in lower-case, but if you make the letter in upper-case, it can take up to ten hours. So if you want to make your account much safer, you should make your password upper-case. Of course, you can also add numbers or symbols to your password. Most of the time a hacker’s computer has to work for 18 days to break a password, but if you choose a nine-letter password that includes numbers and symbols, it can take a hacher’s  computer 44,530 years to break it.
【小题1】Scientists have found that   your password is much safer for  
your account.