所以地球上的火山有好几种类型，而在金星上的火山只有一种。

So while on Earth we have several types of volcanoes, on Venus there's mostly the one type.

youdao

比如，地球比月球含的物质多，所以地球的拉力或引力就比月球大。

For example, the earth has more matter than the moon, so the earth's pull or gravitation is stronger than the moon's.

youdao

由此断定月球的轨道主要由来自太阳的牵引力决定，所以地球对于太阳的轨道一直是椭圆形的。

It follows that the Moon's orbit is primarily determined by the gravitation pull from the Sun, so the orbit of the Earth will always curve towards the Sun.

youdao

So the Earth is an inertial frame of reference, if you go in a train relative to the Earth at constant velocity, you're also inertial.

所以,地球是一个惯性参考系,如果你坐在相对于地球匀速运动的火车里,你也处于惯性状态

耶鲁公开课 - 基础物理课程节选