单选题 At the base of a mountain in Tanzania's Gregory Rift, Lake Natron burns bright red, surrounded by the remains of animals that were unfortunate enough to fall into the salty water. Bats, swallows and more are chemically preserved in the pose in which they perished, sealed in the deposits of sodium carbonate in the water. The lake's landscape is bizarre and deadly—and made even more so by the fact that it's the place where nearly 75 percent of the world's flamingos (火烈鸟) are born. The water is so corrosive that it can burn the skin and eyes of unadapted animals. Flamingos, however, are the only species that actually makes life in the midst of all that death. Once every three or four years, when conditions are right, the lake is covered with the pink birds as they stop flight to breed. Three-quarters of the world's flamingos fly over from other salt lakes in the Rift Valley and nest on salt-crystal islands that appear when the water is at a specific level—too high and the birds can't build their nests, too low and predators can move briskly across the lake bed and attack. When the water hits the fight level, the baby birds are kept safe from predators by a corrosive ditch. 'Flamingos have evolved very leathery skin on their legs so they can tolerate the salt water,' says David Harper, a professor at the University of Leicester. 'Humans cannot, and would die if their legs were exposed for any length of time.' So far this year, water levels have been too high for the flamingos to nest. Some fish, too, have had limited success vacationing at the lake as less salty lagoons (泻湖) form on the outer edges from hot springs flowing into Lake Natron. Three species of tilapia (罗非鱼) thrive there part-time. 'Fish have a refuge in the streams and can expand into the lagoons when the lake is low and the lagoons are separate,' Harper said. 'All the lagoons join when the lake is high and fish must retreat to their stream refuges or die.' Otherwise, no fish are able to survive in the naturally toxic lake. This unique ecosystem may soon be under pressure. The Tanzanian government has once again started mining the lake for soda ash, used for making chemicals, glass and detergents. Although the planned operation will be located more than 40miles away, drawing the soda ash in through pipelines, conservationists worry it could still upset the natural water cycle and breeding grounds. For now, though, life prevails—even in a lake that kills almost everything it touches.

单选题They have developed techniques which are ______ to those used in most factories．

单选题Asia ______ by most experts to be the cradle of human civilization.

单选题It is said that one hundred dollars can hardly ______ one night at a top hotel in Shanghai. A. pay B. cover C. spend D. cost

单选题Give me a（）pecker of chocolates ,please.

单选题Monique is studying business administration because she wants to be a highly paid ______ in a large company.

单选题The children found a ______ of keys in the street.

单选题A: I'm sorry, but he's out to lunch right now. B: ______.

单选题Though this apparatus is expensive, the patient agreed to use it after the operation because it could ______ the pain.

单选题The duty of a soldier is to Udefend/U his country.

单选题She was so obstinate that she wouldn't adjust her opinions. A. inflexible B. alert C. wise D. talented

单选题The news ______ the radio announced surprised everybody.

单选题Cathleen: Let's take a coffee break, shall we?Yolanda: ______ , but I can't.

单选题Why do Mexican (emigrants) in Los Angeles (tend) to have more children than the (impoverished) peasants living (in Mexico City)?

单选题My brother likes eating very much but he isn't very ______ about the food he eats.

单选题None of us has a clear idea about ______ to do.

单选题As computer systems become even more sophisticated, the methods of those who exploit the technology.

单选题A quality education is the ultimate liberator. It can free people from poverty, giving them the power to greatly improve their lives and take a productive place in society. It can also free communities and countries, allowing them to leap forward into periods of wealth and social unity that otherwise would not be possible. For this reason, the international community has committed itself to getting all the world’s children into primary school by 2015, a commitment known as Education for All. Can education for all be achieved by 2015? The answer is definitely “yes”, although it is a difficult task. If we now measure the goal in terms of children successfully completing a minimum of five years of primary school, instead of just enrolling for classes, which used to be the measuring stick for reducation, then the challenge becomes even more difficult. Only 32 countries were formerly believed to be at risk of not achieving education for all on the basis of enrollment rates. The number rises to 88 if completion rates are used as the criterion. Still, the goal is achievable with the right policies and the right support from the international community. 59 of the 88 countries at risk can reach universal primary completion by 2015 if they bring the efficiency and quality of their education systems into line with standards observed in higher-performing systems. They also need significant increases in external financing and technical support. The 29 countries lagging farthest behind will not reach the goal without unprecedented rates of progress. But this is attainable with creative solution, including use of information technologies, flexible and targeted foreign aid, and fewer people living in poverty. A key lesson of experience about what makes development effective is that a country’s capacity to use aid well depends heavily on its policies, institutions and management. Where a country scores well on these criteria, foreign assistance can be highly effective. In the first paragraph, the author suggests that a quality education can______. 

单选题I had to get ______ about the subject before I write the paper. ( )

单选题If you don"t mind, I ______ do my homework than play cards with you.