单选题 He failed the exam, ______ proved that he hadn't been working hard enough.
  • [A] that
  • [B] which
  • [C] what
  • [D] of which


【正确答案】 B
【答案解析】[解析] 本题考查非限制性定语从句。这里关系代词代替整个主句，只能由which引导。