【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】句意：斯蒂芬. 霍金认为：地球不太可能是有生 命进化现象的唯一星球。限定性定语从句中缺少 地点状语，where在此处引导定语从句，作地点状 语，修饰先行词planet。