Once Earth had gone through the finalstages of its formation, gases bubbled to the surface and were held by Earth's gravitational field to form the atmosphere.
一旦地球经历了其形成的最后阶段,气体就会鼓泡到地表,并被地球的重力场控制,形成大气。
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If we had rock samples to study, we'd know whether these small craters were formed by impacts during the finalstages of planetary formation, or if they resulted from later meteor showers.