【题目】Stephen Hawking believes that the earth is unlikely to be the only
planet _______ life has developed gradually.
A. that B. where C. which D. whose
在线课程【答案】B
【解析】
试题分析：考查定语从句：句意：Stephen Hawking认为地球不可能是生命逐渐发展的唯一星球。先行词是the only planet，定语从句缺少地点状语，用where引导定语从句，选B.