问题
单项选择题
月球和地球距太阳的距离差别不大，但表面环境迥然不同。其主要原因是二者的（）
A．质量差异
B．形态差异
C．自转差异
D．公转差异
答案
参考答案：A
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月球和地球距太阳的距离差别不大，但表面环境迥然不同。其主要原因是二者的（）
A．质量差异
B．形态差异
C．自转差异
D．公转差异
参考答案：A
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| Is your schoolbag too heavy? The e-schoolbag will help you. It is said that e-schoolbags are going to be brought into 1 in Chinese middle schools soon. Heavy schoolbags have been a serious 2 for a long time. But the e-schoolbag will 3 . An e-schoolbag is 4 lighter than a usual schoolbag. Perhaps, the e-schoolbag should be 5 an e-textbook. It is a small computer for students. It is as 6 as a usual book, 7 it can still have all the things for study, such as textbooks, exercise books and so on which can be made 8 chips (芯片) like stamps. The students can read the text page by page on the screen, take notes, or even send e-mails to their teachers. They only need to 9 the right chip into the e-schoolbag. Then they can use it. Some people say 10 e-textbooks can be easily broken, while others say it is not good for eyes. But only time will tell. | ||||
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