题目

（新概念4）第35课：下面这句中的“ to travel the quarter of a million miles from the Moon to ..
Because the Moon has only an eightieth of the Earth's mass,it requires 97 per cent less energy to travel the quarter of a million miles from the Moon to Earth-orbit than the 200 mile-journey from Earth's surface into orbit!
为什么辅导书说是做目的状语?为什么我觉得是it的主语后置呢?不是的话it到底指什么?

提问时间：2021-01-09

答案

什么破书,扔掉算了,根本不是状语.
你说的倒是差不多,语法的表述是：
to travel the quarter of a million miles from the Moon to Earth-orbit 是实际的主语；
it 是形式主语,指代的就是to travel the quarter of a million miles from the Moon to Earth-orbit
如果不用形式主语,句子就是：
To travel the quarter of a million miles from the Moon to Earth-orbit requires 97 per cent less energy than the 200 mile-journey from Earth's surface into orbit!
由于主语过长,句子显得头重脚轻,所以用形式主语it,用不定式作实际主语,使句子结构平衡.