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According to the passage, with the increasing rate of Aids, ______.
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人都说西湖的神韵在于______：三面春山如睡，中间盈着一汪湛湛碧水，真有“流出桃花波太软”的娴静；人又说西湖的神韵在于______，依依可人的苏堤白堤上，烟柳画桥，风帘翠幕，这份景致只有天宫仙境可比；人又说西湖的神韵在于______，她云山逶迤，亭台隐现，真有泼墨山水欲露还藏的意趣；人又说西湖的神韵在于她的_______，她那四时八节之景，一山一水一草一木，俱有灵秀之气，冬赏腊梅春折柳，而三秋桂子、十里荷花的美景，更让人流连沉醉。填人横线处最恰当的一项是（）。
That's not good enough, however, the same stability that makes CFC so safe in industrial use makes them extremely longlives, some of the CFCs released today will still be in the atmosphere a century from now. Moreover, each atom of chlorine liberated form. a CFC can break up as many as 100,000 molecules of ozone.
For this reason, governments should ensure the careful handling and recycling of the CFC now in use. When plastic -foam burger holders are broken, the CFCs trapped inside escape. Discarded refrigerators re lease CFCs as well, and, a significant part of the U.S. contribution to CFC emissions comes from draining automobile air conditioners. Such release of CFCs could be prevented if consumers and businesses were offered cash incentives to return broken down air conditioners and refrigerators to auto and appliance dealers. Then the units could be sent back to the manufacturers so that the CFCs could be reused.
While recycling will help, the only sure way to save the ozone is a complete ban on CFC manufacture, which should be phased out over the next five years. Fortunately, as the Montreal Protocal demonstrates, banning CFCs will be far simpler than reducing other dangerous gases. But a ban could admittedly be economically disruptive to the entire world: the annual market for CFCs is some $ 2.2 billion. The Soviet Union, which is a heavy user of CFCs, will have a particularly tough time phasing out the chemicals. "I agree with the ban in principle," said Vladimir Sakharov, a member of the Soviet State Committee for Enviromental Protection,'' but in practice it will be extremely difficult. Our economy is not flexible as others."
To make the transition easier, chemical companies are working hard to find practical substitutes for CF Cs. The most promising approach so far is to use CFC family members that are chemically altered to make them less dangerous to the environment. The chlorine - free substitutes is the 'high cost of making them. It may be that until better manufacturing techniques are developed, consumers will have to pay more for affect ed products. The prospect is not a pleasant one, it is a small price to pay for curbing the green house effect and saving the life -preserving ozone layer.
Why should governments ensure the careful handling and recycling of the CFCs now in use？
Criticism of research lays a significant foundation for future investigative work, but when students begin their own projects, they are likely to find that the standards of validity in field work considerably more rigorous than the standards for most library research. When students are faced with the concrete problem of proof by field demonstration, they usually discover that many of the "important relationships" they may have criticized other researchers for failing to demonstrate are very elusive indeed. They will find, if they submit an outline or questionnaire to their classmates for criticism, that other students make comments similar to some they themselves may have made in discussing previously published research. For example, student researchers are likely to begin with a general question but find themselves forced to narrow its focus. They may learn that questions whose meanings seem perfectly obvious to them are not clearly understood by others, or that questions which seemed entirely objective to them appear to be highly biased to someone else. They usually find that those who have not actually attempted it generally believe the formulation of good research questions is a much more subtle and frustrating task.
What does the author think about trying to find weaknesses in other people's research？
The coming of the railways in the 1830s transformed society and economic life by providing, for the first time, mass transport for passengers and goods. One man, George Stephenson, is sometimes called the "father of the railways" although he did not invent either the locomotive or the rails. The basic idea of a "railway" was an old one, mainly used in mines. In the sixteenth century, miners found it was easier to push their loads in a truck with wooden wheels over planks than to push it through mud and over rocks. Later they developed plateways, which were long pieces of iron fixed to the ground to channel the wheels along, in place of the wooden planks.
So these were the early rails, but what about the locomotives？ Locomotive is short for locomotive engine, which means a self-propeled engine. Steam engines were well - known in mines and factories by the early nineteenth century, and some people had the idea of putting them on wheels as a substitute for human and horse power in pulling loads.
The first such locomotive was built by an English man called Richard Trevithick in the year 1804. His engine worked but there were serious technical problems. The locomotives were very heavy, for example and kept breaking the track. At this stage, they didn’t even offer any economic advantage. So locomotives didn’t really catch on then.
One early enthusiast, though, was George Stephenson, who had been doing various mechanical and engineering jobs at coal mines since he was a boy. He didn't have much formal education, but he was good at fixing things, from shoes to clocks to steam engines. He had devised on ingenious safety lamp for the mines, one that wouldn't cause explosions underground.
The engines at the mines were mostly stationary, fixed machines for pumping water or for winding or hauling loads by cables. But George Stephenson also built a number of experimental locomotives. That’s how he came to be involved, in september 1825, with the opening of an innovative railway line in northern England. Until then, the only railways had been small, private lines carrying coal or metal ores from mines to the nearest fiver or canal. The Stockton and Darlington railway was different. It was a public railway and for this new railway, George Stephenson designed a locomotive called" locomotion" which was used to haul passengers from the first day.
The idea of carrying passengers as well as freight was born and soon turned out, quite unexpectedly, to be a phenomenal success. The booming Industrial Revolution also meant a growing demand for goods trans port, which the railways were able to meet. But although railways were now becoming established, locomotives weren’t. They still faced competition from both horsepower and stationary winding engines. This is really where George Stephenson comes in.
The next big railway project was a fifty-kilometre line to link Liverpool and Manchester, again in northern England. The directions couldn’t decide which method of haulage they should go for. On the whole they favoured winding engines, stationed every two or three kilometres along the track. But Stephenson, who was on the board of directors, argued doggedly in favor of locomotives, and in the end they agreed to offer a prize to see if anyone could build one good enough to do the job. Stephenson entered the contest, of course -- he was competitive by nature anyway -- with a locomotive built by his son, Robert George him self was too busy surveying the railway line but Robert was also an excellent engineer and he designed a magnificent engine called the Rocket, the tree ancestor of the modem steam locomotive.
The most important feature of the Rocket was its multi - tube boiler. Instead of just one wide tube carry ing hot air from the furnace through the water of the boiler, beating it into steam, the Rocket had twenty five little tubes, which gave it a much greater surface area in contact
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