from the moon the earth looks like a beautiful blue planet.A. SeeingB. SeenC. To seeD. S

问题补充：

from the moon, the earth looks like a beautiful blue planet.

A. Seeing

B. Seen

C. To see

D. See

答案：

A. Seeing

(答案→)B. Seen

C. To see

D. See

解析：考查非谓语动词。the earth与See之间是被动关系，故用过去分词。句意：如果地球从月球上被看的话，地球看起来就像一个美丽的蓝色的星球。故选B。