最简分数的分子和分母只有公因数1。()
正确
暂无解析
协调人类和环境关系的首要问题是:()
党的十九大首次把()纳入党的建设总体布局。
人们总是在夜间看到北斗七星绕着北极星在运动:()
No sooner ____ to the station ____ the train left.
Is it the school _________ you used to study _________ they visited yesterday?