题目

如图反映了清朝的历史变迁，导致这一变迁的主要原因有（ ）①社会安定②实行闭关锁国③耕地面积扩大④经济发展 A . ①②③ B . ①②④ C . ①③④ D . ②③④ 答案：CThe teacher seldom let an opportunity to teach his students or to help them make up for the days of schooling they had missed ______.　 A. pass　　 B. passing　　 C. to pass　　　 D. being passed