A．prevent

　　B．stop

　　C．kept

　　D．protect

　　In hot summer,dark glasses will________you from the sunlight.

　　A．prevent

　　B．stop

　　C．kept

　　D．protect

In the atmosphere, carbon dioxide acts rather like a one-way mirror or the glass in the roof of a greenhouse which allows the sun's rays to enter but prevents the heat from escaping.

　　 According to a weather expert' s prediction, the atmosphere will be 3℃ warmer in the year 2050 than it is today, if man continues to burn fuels at the present rate. If this warming up took place, the ice caps in the poles would begin to melt, thus raising sea level several metres and severely flooding coastal cities. Also, the increase in atmospheric temperature would lead to great changes in the climate of the northern hemisphere (北半球), possibly resulting in an alteration of the earth's chief food growing zones.

　　  In the past, concern about a man-made warming of the earth has concentrated on the Arctic because the Antarctic is much colder and has a much thicker ice sheet. But the weather experts are now paying more attention to West Antarctic, which may be affected by only a few degrees of warming, in other words, by a warming on the scale that will possibly take place in the next fifty years from the burning of fuels.

　　  Satellite pictures show that large areas of Antarctic ice are already disappearing. The evidence available suggests that a warming has taken place. This fits the theory that carbon dioxide warms the earth.

　　  However, most of the fuel is burnt in the northern hemisphere, where temperatures seem to be falling. Scientists conclude , therefore, that up to now natural influences on the weather have gone beyond those caused by man. The question is: Which natural cause has most effect on the weather?

　　  One possibility is the variable behavior of the sun. Astronomers at one research station have studied the hot spots and "cold" spots (that is, the relatively less hot spots) on the sun. As the sun rotates (使旋转), every 27. 5 days, it presents hotter or "colder" faces to the earth, and different aspects to different parts of the earth. This seems to have a considerable effect on the distribution of the earth's atmospheric pressure, and consequently on wind circulation. The sun is also changeable over a long term: its heat output goes up and down in cycles, the latest trend being downward.

　　  Scientists are now finding shared relations between models of solar weather interactions and the actual climate over many thousands of years, including the last Ice Age. The problem is that the models are predicting that the world should be entering a new Ice Age and it is not. One way of solving this theoretical difficulty is to assume a delay of thousands of years while the solar effects overcome the inertia (惯性) of the earth's climate. If this is right, the warming effect of carbon dioxide might thus be serving as a useful opposed balance to the sun's fading heat .

66. It can be concluded that a concentration of carbon dioxide in the atmosphere would_________.

   A. mean a warming-up in the Antarctic

   B. raise the temperature of the earth' s surface

C. prevent the sun's rays from reaching the earth's surface

D. explain the cause of  great changes in the climate in the northern hemisphere

67.The article was written to explain ___________. 

A. the greenhouse effect

B. the solar effects on the earth

C. the causes affecting weather

D. the models of solar-weather interactions

68. Although the fuel consumption is greater in the northern hemisphere, temperatures there　seem to be falling. This is__________.

 A. mainly because the levels of carbon dioxide are rising

 B. partly due to changes in the output of solar energy

C. possibly because the ice caps in the poles are melting

D. only due to the effect of the inertia of the earth' s climate

69. On the basis of their models, scientists believe the opinion that__________.

A. the climate of the world should be becoming cooler

B. the new Ice Age will be delayed by the greenhouse effect

C. the man-made warming effect helps to increase the solar effects

D. it will take thousands of years for the inertia of the earth's climate to take effect

70. If the assumption about the delay of a new Ice age is correct, ____________.

A. ice would soon cover the northern hemisphere

B. the greenhouse effect could work in favor of the earth

C. the best way to overcome the cooling effect would be to burn more fuels

D. the increased levels of carbon dioxide in the atmosphere could warm up the earth even more quickly

People are being lured (引诱)onto Facebook with the promise of a fun, free service without realizing they're paying for it by giving up loads of personal information. Facebook then attempts to make money by selling their data to advertisers that want to send targeted messages.

　　Most Facebook users don't realize this is happening. Even if they know what the company is up to, they still have no idea what they're paying for Face book because people don't really know what their personal data is worth.

　　The biggest problem, however, is that the company keeps changing the rules Early on you keep everything private. That was the great thing about facebook you could create own little private network. Last year. The company changed its privacy rules so that many things your city. Your photo, your friends' names-were set, by default (默认)to be shared with every one on the Internet.

　　According to Facebook's vice-president Elliot Schrage, the company is simply making changes to improve its service, and if people don't share information They have a "less satisfying experience".

　　Some critics think this is more about Facebook looking to make more money. In original business model, which involved selling ads and putting then At the side of the pages totally Who wants to look at ads when they're online connecting with their friends?

　　The privacy issue has already landed Facebook in hot water in Washington. In April. Senator Charles Schumer called on Facebook to change its privacy policy. He also urged the Federal Trade Commission to set guidelines for social-networking sites."I think the senator rightly communicated that we had not been clear about what the new products were and how people could choose to use them or not to use them," Schrage admits.

　　I suspect that whatever Facebook has done so far to invade our privacy, it's only the beginning. Which is why I'm considering deactivating(撤销)my account. Facebook is a handy site, but I'm upset by the idea that my information is in the hands of people I don't trust. That's too high a price to pay.

1.What do we learn about Facebook from the first paragraph?

A.It is a website that sends messages to targeted users.

B.It makes money by putting on advertisements.

C.It profits by selling its users' personal data.

D.It provides loads of information to its users.

2.What does the author say about most Facebook users?

A.They are reluctant to give up their personal information.

B.They don't know their personal data enriches Facebook.

C.They don't identify themselves when using the website.

D.They care very little about their personal information.

3.Why does Facebook make changes to its rules according to Elliot Schrage?

A.To render better service to its users.

B.To conform to the Federal guidelines.

C.To improve its users' connectivity.

D.To expand its scope of business.

4.Why does Senator Charles Schumer advocate?

A.Setting guidelines for advertising on websites.

B.Banning the sharing of users' personal information.

C.Formulating regulations for social-networking sites.

D.Removing ads from all social-networking sites.

5.Why does the author plan to cancel his Facebook account?

A.He is dissatisfied with its current service.

B.He finds many of its users untrustworthy.

C.He doesn't want his personal data abused.

D.He is upset by its frequent rule changes.