And no, I don't believe for a second that they have visited Earth already.
不，我连一秒钟也不愿相信外星人们已经造访地球了。
The second map shows Earth at the time of launch. That's time zero.
第二幅地图显示了没有时间显示的地球形成时期。
I say look at earth as a spaceship travelling at 500km a second.
我说把地球看成一个每秒飞行500公里的飞船。
The velocity of the Earth in orbit is about 30 kilometers per second.
地球在轨道里的速度，约为30千米每秒。
The second is: how did they get to Earth at such speed?
其二，它们如何以如此急速到达地球？
They reach the satellite and return to the earth in less than a second.
它们抵达人造卫星再返回地球所用的时间不用一秒钟。
Mercury is the second most dense planet after earth.
水星是第二个在地球上密度最大的行星。
The second was Wumo who controlled the earth.
第二个是管地的乌摩。
If an asteroid hit Earth, it's average speed would be 30kilometers per second.
假如小行星撞击地球，它们的平均撞击速度将达到30公里每秒。
And suddenly the second tree knew he was carrying the king of heaven and earth.
猛然间，第二棵树意识到，他运载着的正是天空和大地之王。
In the second part, rare earth polymer complex photochromic materials were synthesized and applied.
本论文第二部分对稀土配合物光致变色材料进行了合成及应用研究。
Second, the physical form of extraterrestrial species reflects human attitudes toward species on Earth.
第二，外星人的外形反映出人类对于地球物种的态度。
Second, the physical form of extraterrestrial species reflects human attitudes toward species on Earth.
第二，外星人的外形反映出人类对于地球物种的态度。
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