单选题. California has been facing a drought for many years now, with certain areas even having to pump freshwater hundreds of miles to their distribution system. The problem is growing as the population of the state continues to expand. New research has found deep water reserves under the state which could help solve their drought crisis. Previous drilling of wells could only reach depths of 1,000 feet, but due to new pumping practices, water deeper than this can now be extracted (抽取). The team at Stanford investigated the aquifers (地下蓄水层) below this depth and found that reserves may be triple what was previously thought. It is profitable to drill to depths more than 1,000 feet for oil and gas extraction, but only recently in California has it become profitable to pump water from this depth. The aquifers range from 1,000 to 3,000 feet below the ground, which means that pumping will be expensive and there are other concerns. The biggest concern of pumping out water from this deep is the gradual settling down of the land surface. As the water is pumped out, the vacant space left is compacted by the weight of the earth above. Even though pumping from these depths is expensive, it is still cheaper than desalinating (脱盐) the ocean water in the largely coastal state. Some desalination plants exist where feasible, but they are costly to run and can need constant repairs. Wells are much more reliable sources of freshwater, and California is hoping that these deep wells may be the answer to their severe water shortage. One problem with these sources is that the deep water also has a higher level of salt than shallower aquifers. This means that some wells may even need to undergo desalination after extraction, thus increasing the cost. Research from the exhaustive study of groundwater from over 950 drilling logs has just been published. New estimates of the water reserves now go up to 2,700 billion cubic meters of freshwater.1. How could California's drought crisis be solved according to some researchers? ______
单选题. Questions 8 to 11 are based on the conversation you have just heard.1.
单选题《复合题被拆开情况》 U. S. import prices recorded the biggest drop in five months in November as food and fuel costs tumbled 下跌, keeping inflation pressures subdued against the backdrop of a weak economy. The L
单选题《复合题被拆开情况》 Picture this: You’re at a movie theater food stand loading up on snacks. You have a choice of a small, medium or large soda. The small is $ 3.50 and the large is $ 5.50. It’s a tough decisi
单选题. Questions 12 to 15 are based on the conversation you have just heard.5.
单选题. Questions 5 to 7 will be based on the following news item.5.
单选题. Questions 5 to 7 will be based on the following news item.5.
单选题《复合题被拆开情况》 A new study shows that students learn much better through an active, iterative 迭代的 process that involves working through their misconceptions with fellow students and getting immediate feed
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单选题《复合题被拆开情况》 By almost any measure, there is a boom in Internet-based instruction. In just a few years, 34 percent of American universities have begun offering some form of distance learning DL, and amo
单选题《复合题被拆开情况》 Academic dishonesty is nothing new. As long as there have been homework assignments and tests, there have been cheaters. The way that cheating looks has changed over time, though, particula
单选题《复合题被拆开情况》 Soot—also known as black carbon—heats up the atmosphere because it absorbs sunlight. But for years the institutions that focus on climate policy have played down the role of pollutants such
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单选题《复合题被拆开情况》 Health workers who are HIV positive are banned from performing most surgery or dental treatment in case they cut themselves with their instruments and infect patients with their blood. They
单选题. Questions 16 to 18 are based on the passage you have just heard.1.
单选题. Questions 5 to 7 are based on the news report you have just heard.5.
单选题Word on the street is that gossip is the worst.An Ann Landers advice column once characterized gossip as the faceless demon that breaks hearts and ruins careers.The Talmud describes it as a three-pron