问题
选择题
______ 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
答案
答案：B
题目分析：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。