on ten years of observation and study, the theory shows that every one dreams every night, whether they realized it or not.
A. Basing
B. Based
C. Being based
D. Having based
网友回答
A. Basing
(答案→)B. Based
C. Being based
D. Having based
解析：考查非谓语动词作状语。句意：基于十年的观察和研究，这项理论表明，每个人每晚都做梦，不管他们是否意识到这一点。the theory与base之间是被动关系，故用过去分词作状语。选B。