某稀溶液中含有Fe(NO3)3、Cu(NO3)2、HNO3，向其中逐渐加入铁粉，_爱下问搜题

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问题选择题

某稀溶液中含有Fe(NO₃)₃、Cu(NO₃)₂、HNO₃，向其中逐渐加入铁粉，溶液中Fe²^＋的浓度与加入铁粉的物质的量之间的关系如图所示。则溶液中Fe(NO₃)₃、Cu(NO₃)₂、HNO₃物质的量浓度之比为(　　)

A．1∶1∶1

B．1∶3∶1

C．3∶3∶8

D．1∶1∶4

答案

答案：D

解答本题应注意以下三点：(1)Fe与Fe(NO₃)₃、Cu(NO₃)₂、HNO₃反应的先后顺序；(2)横、纵坐标及曲线各折点表示的意义；(3)HNO₃反应生成的Fe³^＋和溶液中的原有Fe³^＋均与Fe发生反应。

判断题

股息通常是按照一定比例事先确定的，这是股息与红利的主要区别（）

完形填空

完形填空（共20小题；每小题1分，满分20分）
During the years when I was a teacher, I learned a lot of things. Perhaps the most important one was the life-changing 16 of encouraging words.
I 17 what Leo Buscaglia had done with his students in University of Southern California. In one class Leo Buscaglia and his students had made two lists of 18 , one positive and one negative. Then they 19 the negative words in the trash and tried to use only the 20 words for one month. They were 21 at how much better their lives became just by using words full of 22 .
I decided to try this as well by 23 something good to write on each paper my students 24 . No matter how many mistakes a student’s paper 25 , there was always a 26 sentence, beautiful thought, or a great idea that I could 27 on. I remember glancing over my desk and 28 some of the students reading those encouraging words 29 . It was a joy seeing their eyes shine a little brighter, their 30 sit up a little straighter, and their learning climb a lot 31 .
I recently saw one of my 32 students and we talked for a while. He has got married, and has two children now. As I was saying goodbye, he said, “You know I 33 have a few of those old papers. I look at them from time to time. I just 34 my kids have a good teacher like you.” I was amazed at the 35 those few positive words had on his life.
May your own life be forever full of encouraging words in your ears, from your lips and in your heart.

B．disappointed

A．astonishment

B．encouragement

C．looked through

A．again and again

B．now and then

C．little by little

D．step by step