what travels around the earth without using any fuel?
问题描述：
what travels around the earth without using any fuel?
答
什么东西可以环游地球而不消耗任何燃料？
of course,nothing except moon.
答
The satellites！without using any fuel but the universal gravitation!
答
什么环绕地球旅行而不消耗任何燃料?
The moon
月亮