题目

 Not until the motorbike looked almost new ______ repairing and cleaning it.   A. he stopped              B. that he stopped   C. that did he stop   D. did he stop 答案：D20世纪中叶，一些新兴企业不愿到匹兹堡落户，其主要原因是①环境污染严重   ②劳动力素质太低   ③地价上涨   ④公共设施不齐全A.①②B.①③C.①④D.②④