21号北美二战了好紧张啊，网上搜到个地月三个理论的大家看看

棒棒糖loli8

明天就考试了压力好大好大。。。网上搜到个地月的大家看看希望有帮助

The Fission Theory: This theory proposes that the Moon was once part of the Earth and somehow separated from the Earth early in the history of the solar system. The present Pacific Ocean basin is the most popular site for the part of the Earth from which the Moon came. This theory was thought possible since the Moon's composition resembles that of the Earth's mantle and a rapidly spinning Earth could have cast off the Moon from its outer layers. However, the present-day Earth-Moon system should contain "fossil evidence" of this rapid spin and it does not. Also, this hypothesis does not have a natural explanation for the extra baking the lunar material has received.

The Capture Theory: This theory proposes that the Moon was formed somewhere else in the solar system, and was later captured by the gravitational field of the Earth. The Moon's different chemical composition could be explained if it formed elsewhere in the solar system, however, capture into the Moon's present orbit is very improbable. Something would have to slow it down by just the right amount at just the right time, and scientists are reluctant to believe in such "fine tuning". Also, this hypothesis does not have a natural explanation for the extra baking the lunar material has received.

The Condensation Theory: This theory proposes that the Moon and the Earth condensed individually from the nebula that formed the solar system, with the Moon formed in orbit around the Earth. However, if the Moon formed in the vicinity of the Earth it should have nearly the same composition. Specifically, it should possess a significant iron core, and it does not. Also, this hypothesis does not have a natural explanation for the extra baking the lunar material has received.

Harecollarbone

同北美21号啊，真相弃考。想想白花花的二百五又舍不得。

棒棒糖loli8

是的呀，不要换库啊不要换库啊==换库数学就完了，DS平时错巨多

Harecollarbone

唉。我才看了20题机经呢。怎么这么多啊~~看死我了。话说你明天在哪边考伐？

棒棒糖loli8

我在boston，你呢

jjh1221

同北美21号，大家加油啊！

棒棒糖loli8

加油啊加油啊，我都不知道今天干嘛了，想想明天要考折磨的4小时我就难过

shaoning

明天，21号考，祈求幸运之神降临

rainyming

同北美21号二战,大家一起加油！！！

Harecollarbone

呀呀，我在Philadelphia，好像有人一起去啊。烦躁的我。