When the algae have done theri work, the atmosphere will become cooler,but befor man can set foot on Venus it will be neccessary for the oxygen to produce rain. The surface of the planet will still be too hot for man to land on it but the rain will eventually fall and in a few years something like earth will be reproduced on Venus.

　　1.Inte long run, the most insoluble problem caused by population growth on earth will probably be the lack of ______.

　　a.food

　　b.oil

　　c.space

　　d.resources

　　2.Carl Sagan believes that Venus might be colonized from earth because _____

　　a.it might be possible to change its atmosphere

　　b.its atmosphere is the same as the earth's

　　c.there is a good supply of water on Venus

　　d.the days on Venus are long enough

　　3.On Venus there is a lot of ________.

　　a.water

　　b.carbon dioxide

　　c.carbon monoxide

　　d.oxygen

　　4.Algae are plants that can____.

　　a.live in very hot temperatures

　　b.live in very cold temperatures

　　c.manufacture oxygen

　　d.all of the above

　　5. Man can land on Venus only when_______.

　　a.the algae have done their work

　　b.the atmosphere becomes cooler

　　c.thereis oxygen

　　d.it rains there

　　答案：cabdd

　　The United States is on the verge of losing its leading place in the world's technology. So says more than one study in recent years. One of the reasons for this decline is the parallel decline in the number of U.S. scientists and engineers.

　　Since 1976,employment of scientists and engineers is up 85 percent. This trend is expected to continue. However, the trend shows that the number of 22-year-olds--the near term source of future PH.D.s-is declining. Further adding to the problem is the increased competition for these candidates from other fields-law,medicine,business,etc. While the number of U.S. PH.D.s in science and engineering declines,the award of PH.D.s to foreign nationals is increasing rapidly.

　　Our inability to motivate students to pursue science and engineering careers at the graduate level is compounded because of the intense demand industry has for bright Bachelor's and Master's degree holders. Too often, promising PH.D.candidates, confronting the cost and financial sacrifice of pursuing their education,find the attraction of industry irresistible.

　　1.The U.S.will come to lose its leading place in technology probably because ________.

　　a. the number of PH.D. degree holders is declining

　　b. the number of scientists and engineers is decreasing

　　c. the number of 22-year-ilds is declining

　　d. scientists and engineers are not employed

　　2.The field of science and engineering is facing a competition from ________ .

　　a. technology

　　b. foreign nationals

　　c. such fields as law, medicine and business

　　d. postgraduates

　　3.Large-scale enterprises now need _______.

　　a. bright graduates and postgraduates

　　b. new inventions

　　c. advanced technology

　　d. engineers

　　4.Many promising postgraduates are unwilling to pursue a PH.D. degree because _________.

　　a. they are not encouraged to be engaged in science

　　b. industry does not require PH.D. holders

　　c. they have financial difficulties

　　d. they will spend much time and energy completing PH.D.

　　5.PH.D. candidates "find the attraction of industry irresistible" means that _________.

　　a. they find industry is attracting more and more college students

　　b. they don't think they can prevent themselves from working for industry

　　c. they cannot resist any attraction from all sides

　　d. they cannot work for industry any longer

　　答案：bcadb