The Earth's orbit around the Sun is an ellipse, which means its distance from the Sun ___ during the year. A. varies B. is invariable C. stabilizes D. disappears 相关知识点: 试题来源: 解析 A。解析:本题考查词汇和语法。“varies”表示变化,地球公转轨道是椭圆,与太阳距离会变化;“is invar...
Low Earth orbit (LEO), region of space where satellites orbit closest to Earth’s surface. There is no official definition of this region, but it is usually considered to be between 160 and 1,600 km (about 100 and 1,000 miles) above Earth. Satellites do