In most towns today, you can see teenagers standing over electronic machines with flashing lights, shooting at spaceships from other planets and dropping bombs on strange monsters（惡魔）.The machines have names like Space Warrior, Dark Invader and so on. It used to be believed that damage was done only to those strange visitors from outer space, but now it seems that they are striking back.?

Many teenagers like electronic games so much that they can't stop playing. They spend hours tightly holding the joystick controls and constantly pressing buttons marked “fire”.They develop pains on their fingers because of the constant pressure. They play and play so that the pains have no chance to cure properly. The rapid wrist movement required to guide the spaceship across the screen causes another problem: The muscles of the wrist and arm become so inflamed and swollen(充血紅腫)that they press against the bones. This condition is what doctors now call “Space Warriar's Wrist”.Other strange aches and pains also are likely to affect（影響）the elbows and shoulders.?

Another even more alarming problem is shown by the case of a 17-year-old girl which was recently in the British Medical Journal. She had been playing all kinds of electronic games for more than two hours a day. Her father repaired games and machines and she could use the cassettes and systems in his workshop as often as she liked. One day, after playing a game called Dark Invader, she lost consciousness(暈倒)and fell to the floor.?

Doctors who examined her found she was suffering from an unusual illness caused by lights flashing at a particular frequency.?

“Space Warrior's Wrist”is caused by_______.?

A. constantly pressing the buttons?

B. rapidly moving across the screen ?

C. tightly holding the joystick controls?

D. inflamed and swollen muscles of the wrist?

The case of a 17-year-old girl by the writer shows that the writer_______.

A. supports playing electronic games?

B. feels very sorry for the girl?

C. disagrees with young people's playing electronic games?

D. feels worried about young people's poor health?

From the passage we can conclude that playing electronic games is _______.

A. enjoyable and helpful to the study?

B. exciting but harmful to the health and study ?

C. interesting but harmless to the eyes?

D. amusing and satisfying

A new study says one part of the human brain may become smaller as the result of a condition known as jet lag. Jet lag results from flying long distances in an airplane. People with jet lag may feel extremely tired for several days. They may also have problems thinking clearly and remembering.?

Recently a researcher at the University of Bristol in Britain reported the findings of his jet lag study, which involved twenty young women who worked for international airlines. They had served passengers on airplanes for five years. These flight attendants flew across many countries and at least seven time zones. In the study, the flight attendants had different amounts of time to recover from jet lag. Half the women spent five days or fewer in their home areas between long flights. The other half spent more than fourteen days in their home areas.?

The researcher took some saliva from the women's mouths to measure levels of a hormone(荷爾蒙) that increases during stress. He tested them to see if they could remember where black spots appeared on a computer screen. And he took pictures of their brains to measure the size of the brain's temporal lobes(腦葉).?

It was found that the women who had less time between flights had smaller right temporal lobes. This area of the brain deals with recognizing and remembering what is seen. The same group performed worse and had slower reaction times on the visual memory test. And their saliva samples showed higher levels of stress hormones.?

The researcher believes the brain needs at least ten days to recover after a long trip. He says airline workers told him their ability to remember got worse after working on planes for about four years. Other studies have shown that increased feelings of stress can cause a loss of cells in the part of the brain that controls memory.?

Scientists say more tests are needed to study the effects of jet lag on the brain. They want to find out if too much jet lag could permanently affect memory.?

According to the text, jet lag _______.?

A. can cause difficulties in speaking

B. can make people feel tired for a few weeks?

C. can be only found in flight attendants

D. can be caused by flying over several time zones?

It can be inferred from the text that _______.

A. the conclusion is refused by many scientists?

B. scientists fear that this research is not done properly?

C. every scientific conclusion needs the support from many tests?

D. the women who were examined in the research were not healthy?

From the result of the research we can see that _______.

A. the women who have longer rest at home show better memory?

B. the women who fly in short time have smaller right temporal lobes?

C. the women who have longer flights fail the memory test?

D. the women who rest more than 14 days produce less hormones?

What is the subject discussed in the text??

A. The cause of jet lag.?

B. A story of a group of flight attendants.?

C. The importance of having enough rest after flights.?

D. A research about the effects of jet lag on the brain.??

WASHINGTON-Laura Straub is a very worried woman. Her job is to find families for foreign teenagers who expect to live with American families in the summer.?

It's not easy, even desperated.?

“We have many children left to place:40 out of 75,”said Straub, who works for a Paris based foreign exchange programme called LEC. ?

When exchange programmes started 50 years ago, more families were willing to help others. For one thing, more mothers stayed home.?

But now, increasing numbers of women work outside the home. Exchange student programmes have struggled in recent years to sign up host families for the 30 000 teenagers who come from abroad every year to have some courses for one year in the United States, as well as the thousands more who take part in summer programmes.

School systems in many parts of the US, unhappy about accepting non-taxpaying students, have also strictly limited the number of exchange students they accept. At the same time, the idea of hosting foreign students is becoming less exotic(異國情調的).?

In searching for host families, who usually receive no pay, exchange programmes are increasingly broadening their requests to include everyone from young couples to the retired.

“We are open to many different types of families,”said Vickie Weiner, eastern regional director for ASSE, a 25-year-old programme that sends about 30 000 teenagers on one?year exchange programmes worldwide.?

“For elderly people, exchange students keep up young—they really do,”said Jean Foster, who is hosting 16-year-old Nina Porst from Denmark.?

Foreign teenagers come to American families with the purpose of _______.

A. finding their parents in America      B. finding good jobs in America?

C. learning the culture of America       D. enjoying the life of America

In the past, Straub's job was easy, because American families _______.?

A. needed more money to live      B. had fewer children to support?

C. had spare rooms to rent     D. were not as busy as now

To deal with the problems in recent years, Straub and her workmates have to _______.

A. ask different kinds of families for help

B. limit the number of the exchange students?

C. borrow much money to pay for the costs

D. force some families to accept students

From the last paragraph we can conclude that _______.

A. exchange students are welcome in America?

B. exchange students must pay much money to the host families?

C. American students don't want to join the exchange programmes?

D. old Americans can benefit from hosting exchange students

_______the doctors really doubt is _______ my mother will recover from the serious disease soon.

A. What; when       B. That; how C. What; whether   D. What; what?

Don't just give me a simple “yes” or “no” to my questions. Explain _______ possible.

A. however     B. whoever     C. whenever   D. whatever?

—Sorry. Jackson,_______ I you clearly. It's too noisy here.?

—I _______ that the party was great.?

A. haven't heard; am saying     B. don't hear; said?

C. didn't hear; was saying      D. can't hear; will say?

The science of medicine, _______ progress has been very rapid lately, is perhaps the most important of all the sciences.

A. to which    B. in which     C. Which D. with which?

So absorbed_____in her work that she didn’t realize I was behind her.

A．had she              B．was she             C．she had      D．she was

The mother,along with her two daughters,________ from the sinking aircraft by a passing ship.

A.have rescued             B.have been rescued?

C.has rescued               D.has been rescued ?

Computers and the advantage _________ gave us _________ being made better use of presently.

A.that;is　      B.they;are?

C.it;was　      D.which;were ?