Question

when compared with the size of the whole earth,the highest mountain doesn't seem high at all.

本句可以直接用compared吗？
不能的话为什么

Answer 1

不可以。 因为when compared with the size of the whole earth 这部分是作状语表条件的。 when=If “如果”， 用分词短语或者状语从句都可。
如果用Compare, 整个句子得改：
Compare the highest mountain with the size of the whole earth, and you will find it doesn't seem high at all.
这个句型熟悉吗？
祈使句（动词原形开头， 表条件） + and + 陈述句（一般用will + 动词原形）
Work hard , and you'll catch up with him.
=If you work hard, you'll catch up with him

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追问

分词作状语可以表示条件啊。。。
compared with the size of the whole earth,the highest mountain doesn't seem high at all.
就像这句：
given more water，the fish couldn't die.

追答

我是说表条件的呀， 怎么回事？

追问

那你说不可以用compared
你第一句话就是：不可以

追答

晕， 我以为你说动词原形，所以我给出了这个句型。
祈使句（动词原形开头， 表条件） + and + 陈述句（一般用will + 动词原形）
Work hard , and you'll catch up with him.
=If you work hard, you'll catch up with him