有一无色溶液，可能大量含有K+、A13+、Ba2+、NH4+、Cl-、SO42-、SO32-、HCO3-中的几种。为确定其成分，做如下实验：①取部分溶液，加入足量Na2O2固体，有气
For a while, my neighborhood was taken ever by an army of joggers（慢跑者）．They were there all the time: early morning, noon, and evenings．There were little old ladies in gray sweats, you
下列关于浓硫酸的叙述中，正确的是( )A．浓硫酸具有吸水性，因而能使蔗糖炭化B．浓硫酸在常温下可迅速与铜片反应放出二氧化硫气体C．浓硫酸是
已知M是△ABC的BC边上的中点，若向量=a,= b，则向量等于( ) A．(a－b) B．(b－a)C．( a＋b) D．(a＋b)
人的下丘脑受损，一般不会影响 （ ） A．内分泌活动的协调 B．体温恒定的维持 C．条件反射的建立 D．血糖含量的相对稳定
某同学为了使反应2HCl + 2Ag＝2AgCl + H2↑能进行，设计了下列四个实验，如下图所示，你认为可行的方案是
---We can use QQ to talk with each other on the Internet. --- Really? Will you please show me _________? A. what to use B. how to use it
After five days’ climbing in the mountain, they reached________they thought was the place they’d been dreaming of.A．that B．whereC．which D．what
