阅读下面的短文，从短文后各题所给的A、B、C、D四个选项中，选出一个可以填入空白处的最佳选项，并在答题卡上将该项涂黑。

Computer games are very popular． It is natural for people to want to　 41 ，so playing against a computer or against a friend on the computer can be　 42　 to stop．“Just one more game，” often turns into another game， then another．

Computer games do have their 43 ． They are excellent for training hand / eye coordination（协调）．Surgeons（外科医生） who played computer games as chitdren are often more skilled．Computer games can also be great for teaching students． The students are open to learning while playing． They can study for longer than a 44　 would be able to teach．Students can also learn at their own speed and not feel pressured to match classmates． And with computers you can 45　 a task as many times as you like． The more you do this， the better you will get， until you can do it perfectly．

But like anything else in life， things should be balanced． Too much time on the com purer can　 46　 your eyes． Regular breaks are needed． If students cannot 47　 playing computer games， they won’t do as well in other areas in their life--not just schoolwork，but in developing important social skills such as how to talk with people and how to work with others as part of a 48 ．And if they are 49　 taking regular exercise，their health will become worse．

Computer games have their place，but people must also remember it is important to 50 a balanced lifestyle．

41．A． win　　　　 B． lose　　　　　　 C． fight　　　　　　　　　 D． race

42．A． easy　　　　 B． necessary　　　　 C． difficult　　　　　　　 D． natural

43．A． rules　　　 B． advantages　　　 C． disadvantages　　　　 D． mistakes

44．A． teacher　　　 B． parent　　　　　　 C． doctor　　　　　　　　　 D． computer

45．A． make　　　 B． practice　　　　 C． put off　　　　　　　　 D． discover

46．A． break　　　 B． hurt　　　　　　 C． relax　　　　　　　　 D． close

47．A． enjoy　　　 B． start　　　　　　 C． stop　　　　　　　　　 D． keep

48．A． family　　　 B． game　　　　　　 C． match　　　　　　　　 D． team

49．A． often　　　 B． no longer　　　　 C． always　　　　　　　　 D． still

50．A． refuse　　　 B． give up　　　　　 C． stay away from　　　　 D． have

Sorry to say, our brains naturally start slowing down at the young age of 30. It used to be thought that this couldn't be helped, but new studies show that people of any age can train their brains to work faster. "Your brain is a learning machine," says University of California scientist Dr. Michael Merzenich. Given the right tools, we can train our brains to act like they did when we were younger. All that's required is the practice designed just for the purpose: a few exercises for the mind.

Merzenich has developed a computer-based training method to speed up the process（过程） in which the brain deals with information (positscience.com). Since much of the data we receive comes through speech, the Brain Fitness Program works with language and hearing to better speed and accuracy （准确性）.Over the course of training, the program starts asking you to tell sounds (between "dog" and "bog", for example) at an increasingly faster speed. It's a bit like tennis instructor, says Merzenich, hitting balls at you faster and faster to keep you challenged. You may start out slow, but before long you're pretty quick.

The biggest finding in brain research in the last ten years is that the brain at any age is highly plastic. If you ask your brain to learn, it will learn. And it may even speed up while in the process. To keep your brain young and plastic you can do one of a million new activities that challenge and excite you：playing table tennis or bridge, doing crossword puzzles, learning a language.... "When it comes to preventing ageing, you really do 'use it or lose it'," says Barbara Sahakian, professor at Cambridge University.

51. According to the new studies, what will happen to our brains?

A. They will not start slowing down until the age of 30

B. They will start working slowly after the age of 30

C. They can work as well as at a young age through certain exercises

D. They can not be improved once they start to slow down

52. The writer mentioned many ways to speed up your brain, EXCEPT_____

A. doing a million new activities　　

B. sleeping as much as possible　

C. playing some intelligent games

D. playing table tennis

53. What can we learn from the text?

A. Using right tools is important for brains’ work.　　

B. Brain research deals with information from the Internet　

C. Dr. Merzenich is a scientist in computer,

D. Many activities can keep our brains young.

54. Which of the following agrees with the writer’s idea?

A. The train methods work better for the old.

B. People should train the brain to stop it from aging.

C. The training of the brain should start at an early age.

D. It is necessary to take part in as many activities as possible.

55. Which one is TRUE according to the passage?

A. If you are 71 years old, your brain is too old to train.

B. You can eat the food to keep your brain young and plastic.

C. Merzenich has developed a computer-based training method to train brains.

D. You will feel younger when you train your brain.