问题 解答题

著名微生物学家巴斯德在研究外界微生物对有机物的影响时设计了如下实验,回答问题:

(1)肉汁能够保存较长时间的是______瓶.

(2)预防食物腐败的根本原理是______.

(3)巴斯德通过长期研究提出了保存酒和牛奶的消毒法是:______.

答案

(1)肉汤腐败的原因是微生物的大量繁殖的结果,空气中有微生物,如果落入瓶中的肉汤中,会使肉汤腐败变质,B瓶的瓶颈弯曲,空气中的微生物只落到了瓶颈的弯曲处,不能进入肉汤,故B瓶中的肉汤能保存较长的时间.

(2)食物腐败的根本原因是微生物的大量繁殖,则预防食物腐败的根本原理就是杀死细菌和真菌,或者抑制它们的繁殖.

(3)巴斯德通过把肉汤煮沸,高温可以杀死肉汤中的微生物,再密封食物,使外界的微生物进不了食物,从而得出保存酒和牛奶的消毒法是高温(巴氏)消毒法.

故答案为:(1)B;(2)杀死细菌和真菌,或抑制他们繁殖;(3)高温(巴氏)消毒法

单项选择题

I remember my math teacher Mr. Young very well. He stood out because the kids made fun of him. He was missing one of his fingers, and always pointed at students with his middle finger.

I was not very good at English and math. No matter how hard I tried, I just could not figure out why I did not understand what all the other kids found so easy to learn.

One day, I was told that if I got one more E on my report card, I would be taken to the" big prison for kids".

I tried really hard for weeks. I just couldn’t understand how to make different parts of members into whole things.

The day before report cards were to come out, I knew that Mr. Young would give me an E ,just like he always did.

I went to Mr. Young and told him that the orphanage was going to send me to the big prison if I got another E on my report card. He told me there was nothing he could do;it would be unfair to the other kids if he gave me a better grade than I had actually earned.

I smiled at him and said, "Mr. Young, do you know how the kids make fun of you because you’re missing your finger" He looked at me, moved his mouth to one side and said nothing.

"They shouldn’t do that to you because you can’t help having a finger, Mr. Young. Just like I can’t help not being able to learn numbers and stuff like that. "I said.

The next day, when I got my report card, I tucked it into one of my books. While on the school bus, I opened it : Geography, B+ ; Mechanical Drawing, C- ; English, D- ; History, C- ; Gym, B+ ; Art, C ; Math, D-.

That math grade was the most favorite one I ever received. Because I knew that someone in the world finally understood what it was like for me to be missing a finger inside my head.

The underlined word"tucked" in the passage most probably means“()”.

A. stuck

B. listed

C. hid

D. copied

问答题 案例分析题