某学生在实验室用高锰酸钾制取氧气，错将其当做氯酸钾，向其中加入了二氧化锰，测得混合物总质量为400g，其中钾元素的质量分数为19.5%，放入试管中加热一段时间后，将所得固体加入足量水搅拌、过滤后，经实验测定得到只含一种溶质的滤液，则该同学加入的MnO₂有多少克（   ）

—明天是晴天吗？—我希望是。

—Will it be fine tomorrow?

—____ ____ ____.

某元素的最常见的化合价为-1价，则该元素的原子最外电子层排布式是（  ）

如图是小红探究“阻力对物体运动的影响”的实验．每次让小车从斜面同一高度由静止滑下，记下小车最终停在水平面上的位置．

阅读理解
    Most of the people in China can have four seasons. However, people in South China have three seasons --- spring, summer and fall. They don't have winters. In north China, people have a cold, dry and windy winter. But people in Kunming only have one season --- spring. It's warm and rainy all the year. You can see green trees and beautiful flowers there. So “ Spring City ”is another name for Kunming.