10. The force that attracts objects in space towards each other, and on the earth pulls them towards the center of the planet is called ____________ (重力).
Exercise 2 根据句意, 用所给的词或词组的最恰当形式填空(注意有多余选项)
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lessen, dissolve, depend on, prevent…(from…), lay, now that, on earth, on the earth, on time, in time, surface, gradually |