问题 问答题 简答题

邻菲罗啉分光光度法测铁的原理是什么?本方法的测定范围多大?

答案

参考答案:

测定原理是,先将水样中的高铁用盐酸羟胺还原成亚铁。在PH值4~5的条件下,亚铁与邻菲罗啉反应生成浅红色的络合物。反应式为:根据此络合物颜色的深浅,用分光光度计测定其浓度。本方法的测定范围为5~200ug/L,测得的结果为水样中的全铁。

阅读理解

阅读理解

    In 1969 I was a young girl working in Toronto. I was from a small town in Ontario and had just

moved to the big city about three months earlier. It was one week before Christmas and I was going

home on the last streetcar of the evening.

   I remember looking at my paycheque(工资单) and asking myself how it was going to endure. At

that time in my life I hardly had enough money to exist on. Bread for supper and oatmeal for breakfast

was the only way I kept hunger at bay.

   I got off the streetcar and started walking up the street, when I suddenly noticed a man was running

after me. I stopped, turned around, seeing that he was black. I snapped, "What do you want?" The man

answered in a soft voice, "I am returning your wallet. You left it on the streetcar seat."

   Because of that man's thoughtfulness, I was allowed the comfort of going home by bus for the summer

holidays. Otherwise, I would have stayed alone in my small room with a hog plate.

   I have never been so ashamed of myself, and that poor, kind man had to walk, who knows how far,

home.

   I recognized immediately that this was wrong of me and it changed my ways forever.

1. What can we learn from the second paragraph?   

A. The writer had no job when the story happened. 

B. The writer were leaving the big city for her hometown. 

C. The writer had little money when the story happened. 

D. The writer's parents were very poor when she was young.

2. What does the underlined word "snapped" most probably mean?

A. To speak in a soft voice.

B. To shout angrily. 

C. To scream for help.

D. To whisper.

3. Why was the black man running after the writer?

A. To rob her.

B. To scare her. 

C. To make friends with her.

D. To return her wallet.

4. What is the writer trying to tell her readers? 

A. Never judge people by their appearance. 

B. She had been struggling to her success. 

C. She had changed a lot since that night. 

D. Being kind to strangers will pay back.

单项选择题 A1/A2型题