题干

通过对实验现象的观察、分析推理得出正确的结论是化学学习的方法之一.对下列实验事实的解释正确的是 (   )

现象

解释

A

KI淀粉溶液中通入Cl2,溶液变蓝

Cl2能与淀粉发生显色反应

B

SO2能使酸性高锰酸钾溶液褪色

SO2具有还原性

C

某溶液中加入硝酸酸化的氯化钡溶液,有白色沉淀生成

该溶液中一定含有SO42

D

铁与稀硝酸反应有气泡产生

铁与稀硝酸发生了置换反应

A:A

B:B

C:C 

D:D

上一题 下一题 0.0难度 选择题 更新时间:2015-08-12 05:33:38

答案(点此获取答案解析)

B

同类题2

根据短文理解,选择正确答案。

    In the spring of my career, I found myself questioning the choice of my life's work. The students did not appear to be motivated; the paperwork was overwhelming (巨大的) and the constant changes of educational direction were discouraging. But I just could not bring myself to do anything else. “Next year,” I would say, “next year I will switch jobs, make more money and have far less stress.” Next year just never came. I am now in my forties. And while I am no longer in the classroom or at the schoolhouse, I remain an educator. It finally dawns on me that there is no other profession that will let me change children's minds and have an impact on their future. For every student that finally “got it”, for every new teacher that said, “You inspired me to stay,” I get the raise that has never quite made it to my paycheck.

    I was on a plane recently and the flight attendant asked my name. When I told him, he said, “I knew that was you! You taught at my elementary school. You made me take my cap off in the building and told me I was handsome.” He then paused and said, “I think I kept my hat on until you saw me, just so I could get that compliment (赞美). Thank you for making me feel special.”

    We have now entered an age where nothing is private and secrets are hard to keep. Your “friends” are counted by simply clicking a button. Face-to-face interactions are seen by many as unnecessary and time-consuming. Of course, we can do anything online, including teaching and learning. But I guess I am just old school. I want to look into your eyes when the answer finally dawns on you.