with the size of the whole earth the biggest ocean does not seem big at all.A. To compar

问题补充：

with the size of the whole earth, the biggest ocean does not seem big at all.

A. To compare

B. When comparing

C. Comparing

D. When compared

答案：

A. To compare

B. When comparing

C. Comparing

(答案→)D. When compared

解析：考察分词作状语用法。The biggest ocean与compare之间构成被动关系，使用过去分词。故D正确。可以认为在compared前面省略了it is.