這句話要分開(kāi)看.It takes the Earth the length of time to revolve once around the Sun.it是形式主語(yǔ),代表a solar day簡(jiǎn)單來(lái)說(shuō),會(huì)有這樣的句子：It takes me an hour to finish my homework.就是這樣的句子.這句話...謝謝你的回答,我的疑問(wèn)是which的用法,這句話可以用which嗎?為什么? 里面是不是省略了that?否則就有2個(gè)謂語(yǔ)了.不可以。which的話是指代the length of time這樣the length of time就變成了主語(yǔ)。花時(shí)間的是earth而不是the length of time謝謝,那么用that為什么不是指代前面的the length of time呢 又不明白了,可否解釋下2種用法的不同.that也是指代前面的the length of time或者這樣A solar day is the length of time that it takes the Earth to revolve once around the Sun.