1、71Scientists are always on the lookout for alternative sources of energy. Today were going to discuss one thats so plentiful they say it could supply more energy than all the coal and oil in the world. Its found in something called gas hydrate and, believe it or not, thats a kind of ice. Thats right
2、. But the water in this ice was way down below the Earths surface when it was frozen, so it was under a lot of pressure. And trapped inside the crystals of ice are individual molecules of methanethats whats in natural gas. All this makes gas hydrate pretty strange stuff. If you touch a match to a pi
3、ece of this ice, itll burst into flame. And when geologists bring a chunk of it up to the surface to study at normal air pressure and temperature, gas hydrate begins to hiss and bubble, and in less than half an hour, the ice melts and the methane inside escapes into the air. Now, as you might guess,
4、 this can make gas hydrate kind of hard for miners to handle. And then theres the problem of where its located in frozen arctic regions or in ocean waters off the Atlantic coast, and up to a mile down. Environmentalists warn that mining it could even be disastrous. Offshore drilling could allow seaw
5、ater to seep down into the huge icy deposits and release tons of methane up into the atmosphere. And methane, our listeners may recall, is a greenhouse gas that could really worsen the problem of global warming. So, gas hydrate may offer some interesting possibilities. But, with all these drawbacks,
6、 Im not going to hold my breath waiting for it to fuel my furnace. 【生词摘录】1. lookout: n. C留神关注2. hydrate: n. C氢氧化物，水合物3. crystal: n. C水晶，晶体4. methane: n.C甲烷，沼气5. match: n. C火柴6. hiss: v. 发出尖锐的咝咝声7. bubble: v. 起泡，冒泡8. arctic: adj. 北极的9. environmentalist: n. C环境保护论者10.disastrous: adj. 灾难性的11.offshore:
7、adj. 近海的12.drilling: n. C 钻井13.greenhouse: n. C温室14.drawback: n. C缺点，障碍15.furnace: n. C炉子72Today, I want to talk about the Cariboo gold rush of 1858, which began when gold was discovered in the frontier town of Quesnel Forks in the Canadian province of British Columbia. By 1861 thousands of men had
8、flocked to the region hoping to strike it rich. Naturally, as the town grew, supplies had to be brought in, and this was done with mules. Now the mules were quite reliable, but there were some drawbacks. For example, a mule carrying a heavy load could travel only 15 miles in a day, meaning that a ty
9、pical trip into Quesnel could take as long as 20 days. So, as the demand for supplies continued to grow, a group of merchants and packers decided to try a new approach, believe it or not, they shipped in a herd of camels. I know that sounds strange, but camel trains had been used quite effectively d
10、uring the California gold rush some 10 years earlier. But the results in the Cariboo region werent quite the same. In fact it was a disaster. The camels couldnt carry the heavier loads the merchants expected them to. Their two-toed feet were perfect for desert travel, but they werent suited for Cari
11、boos rugged mountain terrain. To make matters worse, the mules became very agitated whenever they came across a camel and that caused a lot of accidents on the treacherous mountain trails. The mulepackers went so far as to threaten the camel owners with a lawsuit. But the reason the merchants finall
12、y got rid of the camels is because these animals simply werent cut out for the job.【生词摘录】1. gold rush: 淘金热2. flock: v. 聚集，蜂拥而至3. mule: n. C骡4. reliable: adj. 可靠的，可信赖的5. drawback: n. C缺点，障碍，劣势6. packer: n. C赶牲口运货的人7. herd: n. C兽群8. rugged: adj. 高低不平的，崎岖的9. terrain: n. C地形，地势10.agitated: adj. 不安的，焦虑的1
13、1.treacherous: adj. 变化莫测的12.trail: n. C小路，小径13.lawsuit: n. C诉讼（尤指非刑事案件）73Look at our topographical map and youll see that the middle third of the North American continent from the Rocky Mountains almost to the Mississippi River is pretty flat. This is the Great Plains. This kind of area is sometimes
14、 called a prairie, sometimes a steppe. Thats s-t-e-p-p-e. The defining features are level terrain, dry climate, and an absence of trees. The Great Plains are actually the former bed of a shallow inland sea. Over millions of years, sediment left by glaciers, water, and wind smoothed out the dry sea b
15、ed. As I said, the Great Plaints are bordered on the west by the Rocky Mountains. And its really the Rockies that are responsible for the formation of the grasslands. The mountains are so high that they block the heavy moist air traveling eastward form the Pacific Ocean. Lighter, drier air passes ov
16、er the mountains. Until people intervened with irrigation and farms, only grass could grow on the dry, windy plain. In fact, we can divide the Great Plains into three zones. In the west, where its driest and windiest, the grass is very short. In the eastern zone, theres more rain and grass grows as
17、high as 360 centimeters. In the middle third, theres a mix of grass species that grow to an intermediate height.【生词摘录】1. topographical: adj. 地形学的2. prairie: n. C大草原，牧场3. steppe: n. C大草原，干草原4. level: adj. 平坦的5. terrain: n. 地形6. sediment: n. C沉淀物7. glacier: n. C冰川8. smooth out: v. 消除，使平滑9. moist: n. C
18、潮湿的10.intervene: v. 介入，干预11.windy: adj. 多风的12.intermediate: adj. 中间的74Did you know you can catch a mood? A bad mood isnt spread by a virus like the flu is, but it can be contagious. Moods sort of drift from person to person unconsciously. Slight, unintentional signals carry the mood. Youve probably
19、experienced it yourself. Youre around someone whos feeling down and showing itslumped shoulders, downcast mouth, subdued voiceall that sort of thing. Pretty soon you begin to feel depressed too. Of course, good moods are also catching, not just bad ones. Moods spread in steps. One persons facial exp
20、ression or whatever is observed by another, who then unconsciously begins to mimic. The process is automatica split second mimicry. The person isnt even aware of the copying. A full-blown case of mood transfer develops as this copying continues. Not everyone picks up moods to the same degree. Those
21、whore most susceptible often have strong physiological responses to whats going on around them. You know, people who break out in a nervous sweat easily and whose stomachs churn. People dont all send moods equally well either. The best mood senders are expressive people because mood contagion cant h
22、appen without signals. If they arent therethat is, the person gives no indication of the mood theyre innobody will pick up the mood.【生词摘录】1. virus: n. C病毒2. contagious: adj. 传染性的3. unconsciously: adv. 无意地，不知不觉4. slight: adj. 微小的5. unintentional: adj. 不是故意的，无心的，无意识的6. slumped: adj. 耷拉着的7. downcast: a
23、dj. 气馁的，沮丧的8. subdued: adj. 被抑制的9. catching: adj. 能传染的10.mimic: v. 模仿，仿效11.a split second: 一瞬间12.mimicry: n. C模仿13.full-blown: adj. 全面的14.susceptible: adj. 易受影响的15.physiological: adj. 生理学的16.sweat: v. 出汗17.churn: v. 产生剧烈搅动18.contagion: n. C传染19.indication: n. C 迹象，指示，暗示75Weve probably all wondered h
24、ow a new word gets into the dictionary. Take the word “doofus,“ for example, spelled d-o-o-f-u-s, meaning a stupid or incompetent person. This word, which has been around since the late 1960s in a slang sense, made it into the Merriam-Websters Collegiate Dictionary only in 1993. Why did it take so l
25、ong? Well, first of all, dictionary editors like to wait at least three years to be sure a word is going to last, especially a slang word. They dont want to put in a new word prematurely and then have to take it out in the next edition. But even for words that arent slang, getting into the dictionar
26、y isnt easy. New words have to pass a lot of editorial tests, including how difficult or easy they are to look up. Theres also a limit to how thick a dictionary can be or how small its type can get before people feel they dont want to use it. Some words have to come out before others can go in. The Collegiate Dictionary adds about ten thousand words to every edition, but it takes out only a few hundred, so choices have to be made very carefully.【生词摘录】1. incompetent: adj. 不能胜任的，无能力的2. slang: n. 俚语3. prematurely: adv. 过早地，早熟地4. editorial: adj. 编辑的
