of seniors who have a short-term memory increase of up to 40 percent after exercising just three hours a week. The exercise does not have to be very difficult, but it does have to increase the heart rate. Also, just like the motion for babies, exercise for older people should not be too simple. Learning some new skills or actions, such as with yoga or tai-chi helps to open up memory paths in the brain that may not have been used for a long time. For most people, any type of physical activity that increases the heart rate is helpful. The main aim is to increase the brain's flow of blood. And your brain can benefit from as little as two to three hours of exercise a week.

8. What is the main idea of this passage?

　A. How exercise makes people strong.

　B. How to get good scores on a test.

　C. How exercise helps the brain.

　D. How the brain can change.

9. According to the passage, what is the connection between exercise and brain development?

　A. Exercise helps soften our blood vessels.

　B. Physical exercise helps us think better.

　C. The brain needs special mental exercise.

　D. The more exercise, the bigger the brain.

10. Why does the author think that yoga is fit for seniors?

A. It does good to the joints of old people.

B. It does not increase the heart rate.

C. It includes learning new actions.

D. It can be done in groups.

11. The smallest amount of exercise required to gain any benefit is ________.

A. three hours per week B. 40 hours per week

C. three hours per day D. 40 hours per month

　　D

　　For your next out-of-this-world vacation, you now have the option of literally going out of this world-but it'll cost you $ 40 million. Then again, can you really put a price tag on having the time of your life? According to a new report from Popular Mechanics, Russia is looking to build a luxury hotel in outer space. There you will wake up to a breathtaking blue planet-the earth! The hotel is expected to be stationed on the International Space Station (ISS).

While space tourism itself isn't exactly a novel idea, the notion(概念) of building a hotel out there hasn't been raised before. Really, other companies are still focused on the transportation part of the puzzle-after all, a trip to space is enough for most