离子对色谱主要用于表面活性的()离子、()离子和()络合物的分离。
参考答案:阴;阳;金属
— What happened?
— Thousands of people _____ from their homes because of the earthquake.[ ]
A. flee
B. fled
C. have fled
D. had fled
教师可用相同的课堂管理模式对待不同性质的班级。