题干

“太阳大,地球小,太阳带着地球跑;地球大,月球小,地球带着月亮跑。”重温童谣,结合所学知识,回答童谣中涉及的天体系统层次共有

A:一个

B:两个

C:三个

D:四个

上一题 下一题 0.0难度 选择题 更新时间:2018-06-19 12:09:58

答案(点此获取答案解析)

B

同类题2

阅读理解

    Two thieves came to a house to steal something, they dug a hole in the wall of the house.

    There lived many mice in the house. The woman in the moonlight saw a mouse crawl (爬行) into the house. “Look! In comes one,” she said to the man in the house. He was so frightened that he hurriedly crawled out of the house and said to the one waiting outside, “She found me when I was just in.” But the thief outside didn't believe him, so he said, “Let us two try to crawl into the house together.” At that time two mice happened to crawl into the house, too. The woman saw the mice and shouted, “In come two, catch them!” The two thieves were terribly frightened. The man in the house said, “You saw them come in but where are they? I will catch them tonight.” The two thieves started running away at once.

    The two thieves wanted to make it clear whether they had been found or not the night before. The next day they acted as men selling sweet potatoes and came before the house. The man and the woman were ploughing in their fields. The rein (缰绳) broke and the woman came home for a rope. She saw two men selling sweet potatoes and wanted to buy some. She picked out two which looked like mice. At the time the man couldn't wait for her any longer in the fields and he ran back from the fields to hurry her up. The woman showed the sweet potatoes to the man and said, “How they look like the two of last night.” The man said, “I asked you to fetch a rope, why don't you hurry for it?” The two thieves ran away very quickly without their sweet potatoes.

同类题5

X、Y、Z、W均为短周期元素,它们在元素周期表中的位置如下图所示。若Y原子的最外层电子数是次外层电子数的3倍,下列说法中正确的是                        (    )
X
Y
 
 
Z
W