正确答案: C

sometimes

题目：Sulfur has occasionally been found in the earth in an almost pure state.

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学习资料的答案和解析：

[单选题]第62题应选：

回答下面的题目：UndergrOund Coal Fires Coal burning deep underground in China, India and Indonesia is threatening the environment and human life, scientists have warned. These large scale 51 blazes ( 火焰 ) cause the ground temperature to heat up and kill surrounding vegetation, produce greenhouse gases and can 52 ignite ( 点燃) forest fires, a group of scientists told the annual meeting of the American Association for the Advancement of Science in Denver. The resulting 53 of poisonous elements like mercury can also pollute local water sources and soils, they warned."Coal fires are a global disaster," said Associate Professor Glenn Stracher of East Georgia Collage in Swainsboro, USA. But 54 few people know about them.Coal can heat up on its own, and eventually catch fire and burn, if there is a continuous oxygen supply. The heat produced is not caused to 55 and under the right combinations of sunlight and oxygen, can trigger spontaneous ( 自发的 ) catching fire and burning. This can occur underground, in coal stockpiles, abandoned mines or even as coal is transported. 56 fires in China consume up to 200 million tons of coal per year, delegates were told. In 57 , the U.S. economy consumes about one billion tons of coal annually, said Stracher, 58 analysis of the likely impact of coal fires has been accepted for publication in the International Joomal of Acoal Ecology.. 59 underway, coal fires can burn for decades, even centuries. In the process, they release large 60 of greenhouse gases, poisonous fumes and black particles into the atmosphere.The members of the panel discussed the 61 these fires may be having on global and regional climate change, and agreed that the underground nature of the fires makes them difficult to 62Ultimately, the remote sensing and other techniques should allow scientists to 63 how much carbon dioxide these fires are emitting ( 释放 ). One suggested 64 of containing the fires was presented by Gary Colaizzi, of the engineering firm Goodson, which has developed a heat-resistant grout ( 灌浆 ), which is designed to be pumped into the coal fire to 65 the oxygen supply.第51题应选：

detect

解析：【解析】句意为：他们一致认为地下火灾的性质使得他们很难__________。四个选项：A．develop，发展；B．relieve，释放；C．detect，察觉；D．supply，供应。

[单选题]请在第__62__处填上正确答案。

根据材料，完成下面的题目。UFOS       Sixty years ago, a. man named Kenneth Arnold saw something that we can still (51) today -- something that changed popular culture for ever.Flying his plane over mountains in the U. S. state of Washington, he saw a,line of strange objects, either crescent-shaped (月牙形的) or disc-like, flying (52) the motion of a saucer (碟) skimming (飞速掠过) on water.       The media soon picked up on the story -- the Flying Saucers were here] Was the earth being (53) by creatures from another planet? Soon, So many sightings were made that the U. S. military began to (54) It called these strange Objects UFOs – Unidentified Flying Objects, and that is how they are (55) today.       Military investigations found no evidence of visitors from outer space. But that did not stop the true (56) The military were (57) up, they said. Or maybe it was because the travelers from space were of such superior intelligence (58) they could hide from military analysts (分析家).People have always seen strange lights in the sky. In the past these were explained in (59) ways. In a world where religion was less influential and science fiction was popular, signs from God were replaced by visitors from other (60).       The date of the first UFO sightings was also significant. In 1947, World War II had just ended and the (61) War was just .beginning. Humanity seemed locked in endless conflicts. Like generations before them, people looked (62) the skies for help. But instead of seeking God, they looked for help from super-intelligent aliens (外星人) with (63) technology. Belief in UFOs became the first religion of science.However, even people who believe in UFOs are not quite sure why they visit the earth.The universe is a big place and it is (64) to assume that there is life somewhere out there. It is possible that aliens have worked out how to travel through space. Yet some people report that they have been taken by aliens and have had experiments (65) on them. Why would anyone travel across half the universe to conduct medical experiments on people living in small towns in the United States?请在第__51__处填上正确答案。

to

解析：【题 干】就像先辈们一样，人们——天空寻求帮助。A．在……上面B．朝向 C．在D．N_k【解 析】本题考查介词。没有look above这样的搭配；look t0的意思是“朝……看”；look at是“看着”，没有任何方向的含义；look up的意思“查找”。根据题意，本题选择B。

[单选题]请在第____处填上正确答案。

根据以下资料，回答下面的题目。 请在第____处填上正确答案。

解析：句意：瑞士作家艾里希•冯•达尼肯写道：“纳斯卡线被设计作为UF0的降落地点。”本处后一句However，it would probably be very tricky to land a spaceship in the middle of pic— tures of dogs and monkeys有关键词land a spaceship，而与D项内容的landing place for UF()s形成呼应，所以本题选D。