根据短文内容，判断下列句子正误。正确的用“A”表示，不正确的用“B”表示。
Is an earthquake dangerous? Yes, of course. But this doesn’t mean you can’t do anything about it. If you know what to do in an earthquake, you can be safe.
Keep a cool head. Worry may cause bad decisions. Don’t follow others blindly. Think about what you should do. The first several minutes are important.
If you are indoors during an earthquake, quickly move to a safe place in the room such as under a desk or table. Take care of your head. Stay away from windows and things that may fall and hurt you.
If you are in a crowded room and far away from the door, don’t rush to it. You will find too many people trying to escape at the same time. Instead, stay under a desk or table. Don’t use an elevator. You may not get out of it.
Stay in a safe place until you are sure it’s OK to leave. Some aftershocks (余震) may follow an earthquake. These are as dangerous as the earthquake.
If you are in debris (废墟), try to free your hands and legs. You may make noises by hitting stones. Shouting will make you tired. Try to find some water and food. They are important for you if you aren’t found in a short time. Wait patiently for help.
【小题1】Don’t stay near the windows if you are indoors during an earthquake.
【小题2】You may not get out if you use an elevator during an earthquake.
【小题3】Rush to the door together if you are in a crowded room in an earthquake.
【小题4】Keep staying in a safe place until you are sure it’s OK to leave after an earthquake.
【小题5】You should keep shouting until others hear you if you are in debris.

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.