One impetus for the policy is that companies are already starting to build massive constellations, comprising hundreds or thousands of satellites with many moving parts among them.
2019年6月六级真题(第二套)阅读 Section C
柯林斯高阶英汉双解学习词典释义
N-UNCOUNT
推动;促进;推动力
Something that gives a process impetus or an impetus makes it happen or progress more quickly.