If he it, he it.
A. had seen; could have believed
B. saw; couldn’t believe
C. saw; couldn’t have believed
D. has seen; had believed
网友回答
(答案→)A. had seen; could have believed
B. saw; couldn’t believe
C. saw; couldn’t have believed
D. has seen; had believed
解析：考察虚拟语气.句意:如果他看见了它,他可能已经相信了. 表示与过去事实相反的假设，if 从句的谓语形式用过去完成时即had＋过去分词; “could+have+done”是虚拟语气，表示对过去事情的假设，意思是本来能够做某事而没有做。故选A.