完整的句子是：

It takes Earth 24 hours to complete a rotation on its axis, and roughly 365 days to complete an orbit around the sun. 

汉语译文是：

地球要花费24小时完成绕地轴一周的自转，花费大约365天完成绕太阳一周的公转。

▲ take在这里的意思是“持续，需要，花费”，是句子的谓语；it为形式主语，不定式为真正的主语。以下几种句式表达的意义都是相同的：

I took three hours to get home last night. 昨天晚上我花了三个钟头才到家。

= It took me three hours to get home last night.

= It took three hours for me to get home last night.

It takes the Earth 24 hours to complete a rotation.

请问这句话中take起什么作用呀？

【答】在这句话中，It 是形式主语，takes 是谓语动词，意思是“需要”/ “花费”，the Earth 24 hours 是宾语，to complete a rotation 是真正的主语，即：It takes the Earth 24 hours to complete a rotation.= To complete a rotation takes the Earth 24 hours .全句的结构是：“It + takes/took + 人（或物）+ 段时间 + 动词不定式”。例如：It took me three hours to get home last night. 昨晚我花了三个小时才到家。（摘自《牛津英语用法指南》第三版576.4节）

It takes the Earth 24 hours to complete a rotation

=地球自转一周需要花费（地球）24小时时间

回答如下，以上结构为动词不定式做真正主语，IT 做形式主语结构

It take (sb/sth)+时间+to do sth

=To do sth +take (sb/sth)+时间

To finish the work took them seven days.

=It took them seven days to finish the work.

sth+take+时间+to do sth