单选题 While he was stealing into the classroom, he ______ by his teacher.
  • A. happened to see
  • B. was happened to see
  • C. was happened to be seen
  • D. happened to be seen
【正确答案】 D
【答案解析】[解析] happen表示发生时，永远不能用被动式。除happen外，还有：take place，come about，occur等都不能用被动式。但被人看到必须用被动式。