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【单选题】
Contrary to popular belief, 'falling stars' are not stars at all, but are meteors, solid bodies that travel throng space. Meteor, ranging in size from that of a pinhead, to many tons, are visible to the naked eye at night, when the friction between the surfaces of the meteors and of the air, produces heat as the meteors enter the earth's atmosphere. The intense heat burns up the meteors, which leave a blazing trail of light in their wake. Most meteors do burn up when they enter the earth's atmosphere, with the exception of the large mete- ors, which are dragged through the earth's atmosphere by the earth's gravitational pull. After successful landings upon the earth, these huge bodies are renamed meteorites. Some scientists theorize that thousands of meteors fall to the earth during the daytime and the nighttime, but this theory is impossible to prove or to disprove, as most would necessarily land in water, which covers most of the earth's surface. Generally speaking, meteors and meteor particles travel together in swarms like bees, with the exception of the loners, and travel in any direction they choose. Nature's spectacular fireworks show, a 'meteor shower', comes into view when the swarms encounter the upper layer of the earth's atmosphere during the earth's perpetual revolution around the sun. The friction produced when the meteors and the meteor particles rub against the atmospheric air, and they fall towards the earth in a brilliant display of light. The source of meteors traveling through space has yet to be explained satisfactorily. For thousands of years, the common belief held, was that meteors, or 'falling stars,' were literally from out of this world. In 467 BC, Roman historians recorded the extraordinary fall of a meteor to the earth. Today, astronomers support the theory that comets spawn the swarms. The comets' offspring, the mete- or swarms, travel in regular orbits, similar to the earth's orbit around the sun. One must be quite patient to witness such a swarm, or a meteor shower, as the swarms cross the earth's path only once every 33 years. This spectacle of light is, however, well worth the wait. Meteors were believed to be 'falling stars' NOT in that ______.
A.
they themselves can send out light and heat
B.
they look like stars
C.
they are from out of the world
D.
they are moving downward
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参考答案:
举一反三
【单选题】配料时温度比规定温度高3~5°C,属于( )。
A.
微小偏差
B.
一般偏差
C.
重大偏差
D.
次要偏差
【单选题】属于巨粒组的是()。
A.
粘粒
B.
粗砂
C.
卵石
D.
粗砾
【多选题】新斯的明的药理作用有
A.
治疗重症肌无力
B.
治疗术后肠胀气
C.
室上性阵发性心动过速
D.
室性心动过速
【单选题】冠心病可改变的危险因素不包括( )
A.
高血压
B.
肥胖
C.
糖尿病
D.
年龄
【判断题】21世纪这一时代是一个高度敬仰纯艺术的时代。()
A.
正确
B.
错误
【单选题】属于巨粒组的是( )。
A.
粘粒
B.
粗砂
C.
中砂
D.
块石
【单选题】What she said surprised me. 2. Where she went is none of your business. 3. Why they left the country is a secret. 4. How much it costs is a big problem. 5. Whether she comes or not are unimportant to ...
A.
1
B.
2
C.
3
D.
4
E.
5
【单选题】下列要素中,属于经济法律关系核心要素的是( )。
A.
4
B.
经济法律关系主体
C.
经济法律关系客体
D.
经济法律关系内容
E.
经济权利
【单选题】以下哪项是冠心病可改变的危险因素(单选)
A.
遗传
B.
肥胖
C.
年龄
D.
性别
【简答题】译林版六年级下册英语Unit8补充习题答案
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