C
The term "multitasking" originally referred to a computer's ability to carry out several tasks at one time. For many people, multitasking has become a way of life and even a key to success. In fact, some excellent mental aerobic exercises (大脑训练) involve engaging the brain in two or more challenging activities at a time. Although checking e-mail while talking on a phone and reading the newspaper may be second nature for some people, many times multitasking can make us less productive, rather than more. And studies show that too much multitasking can lead to increased stress, anxiety and memory loss.

In order to multitask, the brain uses an area known as the prefrontal cortex (前额叶脑皮层). Brian scans of volunteers performing multiple tasks together show that as they shift from task to task, this front part of the brain actually takes a moment of rest between tasks. You may have experienced a prefrontal cortex “moment of rest” yourself if you've ever dialed (拨电话) a phone number and suddenly forgotten who you dialed when the line is answered. What probably occurred is that between the dialing and the answering, your mind shifted to anther thought or task, and then took that "moment" to come back. Research has also shown that for many volunteers, job efficiency (效率) declines while multitasking, as compared to when they perform only one task at a time.

Multitasking is easiest when at least one of the tasks is habitual, or requires little thought. Most people don't find it difficult to eat and read the newspaper at the same time. however, when two or more attention-requiring tasks are attempted at one time, people sometimes make mistakes.

We often don't remember things as well when we're trying to manage several details at the same time. Without mental focus, we may not pay enough attention to new information coming in, so it never makes it into our memory stores. That is one of the main reasons we forget people's names---even sometimes right after they have introduced themselves. Multitasking can also affect our relationships. If someone checks their e-mail while on the phone with a friend, they may come off as absent-minded or disinterested. It can also cause that person to miss or overlook key information being passed on to them.

49. Why are some mental aerobic exercises designed to engage people in multitasking?
A.To make them more productive. B.To reduce their stress and anxiety.
C.To develop their communication skills. D.To help them perform daily tasks more easily.
50. according to Paragraph 2, why may a person suddenly forget who has called?
A.He may leave his prefrontal cortex temporarily damaged.
B.He is probably interrupted by another task.
C.He is probably not very familiar with the person he has called.
D.He may need a rest between dialing and speaking.
51. People tend to make mistake when ________.
A.they perform several challenging tasks at a time.
B.new messages are processed one after another
C.their relationships with others are affected
D.the tasks require little thought
52. What is the main idea of the passage?
A.Multitasking has become a way of life.
B.Multitasking often leads to efficiency decline.
C.Multitasking exercises need to be improved.
D.Multitasking enables people to remember things better.

D
My family and I lived across the street from Southway Park since I was four years old. Then just last year they city put a chain link fence around the park and started bulldozing (用推土机推平) the trees and grass to make way for a new apartment complex. When I saw the fence and bulldozers, I asked myself, "Why don't they just leave it alone?"

Looking back, I think what sentenced the part to oblivion (别遗忘) was the drought (旱灾) we had about four years ago. Up until then, Southway Park was a nice green park with plenty of trees and a public swimming pool. My friends and I roller-skated on the sidewalks, climbed the tress, and swam in the pool all the years I was growing up. The park was almost like my own yard. Then the summer I was fifteen the drought came and things changed.

There had been almost no rain at all that year. The city stopped watering the park grass. Within a few weeks I found myself living across the street from a huge brown desert. Leaves fell off the park tress, and pretty soon the trees started dying, too. Next, the park swimming pool was closed. The city cut down on the work force that kept the park, and pretty soon it just got too ugly and dirty to enjoy anymore.

As the drought lasted into the fall, the park got worse every month. The rubbish piled up or blew across the brown grass. Soon the only people in the park were beggars and other people down on their luck. People said drugs were being sold or traded there now. The park had gotten scary, and my mother told us kids not to go there anymore.

The drought finally ended and things seemed to get back to normal, that is, everything but the park. It had gotten into such bad shape that the city just let it stay that way. Then about six months ago I heard that the city was going to "redevelop" certain worn-out areas of the city. It turned out that the city had planned to get rid of the park, sell the land and let someone build rows of apartment buildings on it.

The chain-link fencing and the bulldozers did their work. Now we live across the street from six rows of apartment buildings. Each of them is three units high and stretches a block in each direction. The neighborhood has changed without the park. The streets I used to play in are jammed with cars now. Things will never be the same again. Sometimes I wonder, though, what changes another drought would make in the way things are today.

53. How did the writer feel when he saw the fence and bulldozers?
A.Scared. B.Confused. C.Upset. D.Curious.
54. Why was the writer told not to go to the park by his mother?
A.It was being rebuilt. B.It was dangerous.
C.It because crowded. D.It had turned into a desert.
55. according to the writer, what eventually brought about the disappearance of the park?
A.The drought. B.The crime.
C.The beggars and the rubbish. D.The decisions of the city.
56. The last sentence of the passage implies that if another drought came, ________.
A.the situation would be much worse
B.people would have to desert their homes
C.the city would be fully prepared in advance
D.the city would have to redevelop the neighborhood