单选题 Although ______ happened in that developed country sounds like science fiction, it could occur elsewhere in the world.
【正确答案】 B
【答案解析】本题考查的是主语从句。What可以引导主语从句，本句中what引导的主语从句做整个句子分句的主语，同时what也是主语从句动词happen的主语。其他选项不能引导主语从句。