单选题 After I ______ for half an hour, I realized that he was not coming.
  • A) have waited
  • B) waited
  • C) had been waiting
  • D) was waiting


【正确答案】 C
【答案解析】[解析] 该句的主句是一般过去时(realized)，从句的谓语动词(wait)表示的动作发生在主句谓语(realize)之前，构成了过去的过去，也就是过去完成时，而且已经持续了一段时间，所以应该用过去完成进行时，表示动作(wait)发生在过去的过去，并一直持续到了过去某一时间。