【题目】____ with the size of the whole earth, the highest mountain doesn't see m high at all.
A.To compare
B.While comparing
C.It comparing
D.When compared

【答案】D
【解析】考查过去分词。过去分词作状语，mountain与compare是动宾关系。when compared 这道题是考语法中的省略.即当主句和从句的主语一致时从句的主语+be可省略.所以选,when compared=when (it is ) compared.故选D。