题目内容
Human beings are animals. We breathe, eat and digest, and reproduce the same life (21) common to all animals. In a biological laboratory rats, monkeys, and humans seem very much the same. However, biological understanding is not enough: (22) itself, it can never tell us what human beings are. (23) to our physical equipment the naked human body--we are not an (24) animal. We are tropical creatures, (25) hairless and sensitive to cold. We are not fast and have neither claws nor sharp teeth to defend ourselves. We need a lot of food but have almost no physical equipment to help us get it. In the purely physical (26) , our species seems a poor (27) for survival. But we have survived--survived and multiplied and (28) the earth. Some day we will have a (29) living on the moon, a place with neither air nor water and with temperatures that turn gases into solids. How can we have done all these things Part of the answer is physical. (30) its limitations, our physical equipment has some important (31) . We have excellent vision and hands that can (30) objects with a precision unmatched by any other (33) . Most importantly, we have a large brain with an almost (34) number of neural (35) .
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发电厂和变电所的控制电缆和绝缘导线按机械强度要求。 弱电控制回路导体截面(铜芯)应不小于( )。
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Questions 11-13Complete the sentences below.Choose NO MORE THAN THREE WORDS from the passage for each answer.Write your answers in boxes 11-13 on your answer sheet. （）largely ignored environmental considerations, making no provision for open space and causing other problems.
To get from Kathmandu to the tiny village in Nepal, Dave Irvine-Halliday spent more than two days. When he arrived, he found villagers working and reading around battery-powered lamps equipped with light-emitting diodes, or LEDs--the same lamps he had left there in 2000. Irvine-Halliday, an American photonics engineer, was not surprised. He chose to use LED bulbs because they are rugged, portable, long-lived, and, extremely efficient. Each of his lamps produces a useful amount of illumination from just one watt of power. Villagers use them about four hours each night, then top off the battery by pedaling a generator for half an hour. The cool, steady beam is a huge improvement over lamps still common in developing countries. In fact, LEDs have big advantages over familiar incandescent (白炽的) lights as well--so much so that Irvine-Halliday expects LEDs will eventually take over from Thomas Edison’s old lightbulb as the world’s main source of artificial illumination. The dawn of LEDs began about 40 years ago, but early LEDs produced red or green glows suitable mainly for displays in digital clocks and calculators. A decade ago, engineers invented a semiconductor crystal made of an aluminum compound that produced a much brighter red light. Around the same time, a Japanese engineer developed the first practical blue LED. This small advance had a huge impact because blue, green, and red LEDs can be combined to create most of the colors of the rainbow, just as that in a color television picture. These days, high-intensity color LEDs are showing up everywhere such as the traffic lights. The reasons for the rapid switchover are simple. Incandescent bulbs have to be replaced annually, but LED traffic lights should last five to yen years. LEDs also use 80 to 90 percent less electricity than the conventional signals they replace. Collectively, the new traffic lights save at least 400 million kilowatt-hours a year in the United States. Much bigger savings await if LEDs can supplant Mr. Edison’s bulb at the office and in the living room. Creating a white-light LED that is energy-saving, cheap and appealing has proved a tough engineering challenge. But all the major lightbulb makers--including General Electric, Philips, and Osram-Sylvania--are teaming up with semiconductor manufacturers to make it happen. From the first paragraph, we can see that Dave Irvine-Halliday ______.
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