单选题
阅读下面的短文，文中有15处空白，每处空白给出了4个选项，请根据短文的内容从4个选项中选择1个最佳答案。
{{B}}
Where Have All Our Visitors Gone?{{/B}}

Sixty years ago, a man named Kenneth Arnold saw something that people are still {{U}}(51) {{/U}} today -something that changed popular culture for ever.
Flying his plane over mountains in the US state of Washington, he saw a line of strange objects, either crescent -shaped or disc-like, flying {{U}}(52) {{/U}} the motion of a saucer skimming on water.
The media soon picked up on the story -the Flying Saucers were here! Was the earth being {{U}}(53) {{/U}} by creatures from another planet? Soon, so many sightings were made that the US military began to {{U}}(54) {{/U}}. It called these strange objects UFOs -Unidentified Flying Objects, and that is how they are {{U}}(55) {{/U}} today.
Military investigations found no evidence of visitors from outer space. But that did not stop the true {{U}}(56) {{/U}}. The military were {{U}}(57) {{/U}} up, they said. Or {{U}}(58) {{/U}} it was because the travelers from space were of such superior intelligence that they could hide from the most sophisticated military analysts.
People have always seen strange lights in the sky. In the past these were explained in {{U}}(59) {{/U}} ways. In a world where religion was less influential and science fiction was popular, signs from god were replaced by visitors from other {{U}}(60) {{/U}}.
The date of the first UFO signings was also significant. In 1947, World War Ⅱ had just ended and the {{U}}(61) {{/U}} war was just beginning. Humanity seemed locked in endless conflicts. Like generations before them, people looked {{U}}(62) {{/U}} the skies for help. But instead of seeking God, they looked for help from super-intelligent aliens with {{U}}(63) {{/U}} 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 {{U}}(64) {{/U}} 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 {{U}}(65) {{/U}} on them. Why would anyone travel across half the universe to conduct medical experiments on people living in small towns in the United States?
【正确答案】 B
【答案解析】see和look、seek这三个词的根本性的区别在于see有一个终点(end point)，而 look和seek是没有终点的。句子相关部分说的是“某物人们今天仍然看得见的”。注意“看得见”和“看见”是有终点的，但是“看”没有，因此用seeing而不用looking和seeking。
【正确答案】 C
【答案解析】四个词都是介词。其中below、underneath和under是方位介词；with是方式介词。由于“the motion...”不是方位，因此应选择with。句子相关部分说的是：……以碟子飞速掠过水面的移动方式飞着。
【正确答案】 D
【答案解析】rule：统治；bombard：轰炸；capture：夺取；visit：访问。第三段的第一句话说的是：军事调查并没有发现证据，可以说明从外层空间来了客人了。visitor(客人或访问者)是visit(访问)的派生名词。因此用visited比较好。
【正确答案】 A
【答案解析】investigate：调查；attack：攻击；shoot：射击；confront：对峙。想到军队我们就会想到他们会攻击、射击入侵者或跟他们对峙。但是根据第三段第一个句子中的 military investigations的线索，我们应该选择investigate。
【正确答案】 C
【答案解析】有些读者很可能选择called。这没有错。但是整个小句只是重复了一下上一个小句的信息。用了known意义上就不再重复。
【正确答案】 A
【答案解析】这四个词的意思是：believers：相信的人；thinkers：思想家：followers：追随者；liars：说谎者。可以看出，最合适的词是believers。
【正确答案】 B
【答案解析】hide：藏起来；cover：掩盖；cheat：欺骗；trick：欺骗。从中文的翻译看似乎都可以，但是只有cover可以跟up搭配。因此选择coveting。
【正确答案】 D
【答案解析】这四个都是副词，意思是：definitely；肯定地；undoubtedly：毫无疑问地 necessarily：必定地；maybe：可能。相关句子的第一个词是o，(或者)，表示两种情况都有可能，因此只有用maybe在语义上才是一致的。
【正确答案】 C
【答案解析】awkward：笨拙的；crude：生硬的；religious：宗教的；foolish：傻的。从紧随其后的句子“In a world where religion was less influential…”(在一个宗教的影响不如以前的……世界里)，可以看出合适的选项是religious。
【正确答案】 A
【答案解析】四个词的意思是：planet：行星；continent：洲；country：国家；region；地区。本文的主题是讲不明飞行物，也就是讲来自外星球的人，因此合适的选择是planets。
【正确答案】 D
【答案解析】cool：凉的；star：星球；nuclear：核；cold：冷。正确地回答这道题需要有一点世界知识。第二次世界大战结束后冷战开始，因此选择cold是正确的。星球大战(star war)的提出是里根。核战争(nuclear war)如果会发生的话，文明早就消失了，cold war是冷战，
【正确答案】 B
【答案解析】这四个都是介词：above：上；to：对；at：在；up：上。look above是往上看。 look to是依赖，Look to…for…是指在什么方面依赖。因此，to是合适的选择。相关的句子说的是：跟先辈们一样，人们乞求天来帮助他们。look at是看的意思，动作没有终点。Look up是往上看，当然也还有其它的意思。
【正确答案】 D
【答案解析】这些词的意思是，traditional：传统的； backward：落后的； classical：古典的； advanced：先进的。如果真有外星人来拜会我们的话，那么他们的技术要比我们先进，这个推理可以帮助我们选advanced。
【正确答案】 C
【答案解析】四个词的意思是：unthinkable：不可想象的； impossible：不可能的； reasonable：合理的；insensible：不知道的。上一个小句说的是：宇宙是一个很大的地方，从这句话可以推出，我们有理由假设在那儿有生命的存在，因此，选reasonable是对的。
【正确答案】 A
【答案解析】perform：做；cant：拿；bring：带；take：拿；这是这四个词的基本意义，根据它们的基本意义，用performed比较合适，如果用carried的话需要加out。