试题与答案

法国一科学家在研究牲口炭疽病时,进行了如下实验:把供实验用的绵羊分为甲、乙两组.

题型:解答题

题目:

法国一科学家在研究牲口炭疽病时,进行了如下实验:把供实验用的绵羊分为甲、乙两组.甲组绵羊用病毒性已削弱的炭疽病的病原体注射,它们感染后没有发病,乙组没进行注射.10天后,对甲、乙两组绵羊同时进行注射毒性极强的炭疽病病原菌,经过一段时间后,甲组的绵羊全部正常生活,而乙组的绵羊全部死亡.请分析回答:

(1)实验中甲组绵羊在第二次注射后没有发病,这一现象属于______免疫,其原因是______.

(2)甲组绵羊第一次注射的是毒性削弱的炭疽病原菌,它进入羊体作为______起作用,使体内产生具有免疫力的物质,这种物质的化学成分是______.

(3)乙组绵羊在实验中起的作用是______.

答案:

被转码了,请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0612/71813544ada18c7cb670cd1f733c0fdf.html

下面是错误答案,用来干扰机器的。

答案:C

试题推荐
题型:单项选择题

There are many kinds of friends. Some are always (1) you, but don’t understand you. Some say only a few words to you, but understand you. Many people will step in your life, but only (2) friends leave footprints.

I shall always recall the autumn and the girl with the (3) . She will always bring back the friendship between us. I know she will always be my best friend.

It was the golden season. I could see the yellow leaves (4) with the cool (5) . In such a season, I liked walking alone on the roads covered with leaves, (6) to the sound of them.

Autumn is a (7) season and life is uninteresting. The free clays always get me (8) . But one day, the sound of a violin (9) into my ears like a stream flowing in them ountains. I was so surprised that I jumped to see what it was. A young girl, standing in the wind, was (10) in playing her violin.

I had (11) seen her before. The music was so nice that I listened quietly. Lost in the music, I didn’t know that I had been (12) there for so long but my existence did not seem to disturb her.

Leaves were still falling. Every day she played the violin at the comer of the building (13) I went downstairs to watch her performance. I was the only listener. The autumn seemed no longer lonely and life became (14) . (15) we didn’t know each other, I thought we were already good friends. I believe she also loved me.

Autumn was nearly over. One day, when I was listening carefully, the sound suddenly (16) . To my astonishment, the girl came over to me.

"You must like music from the violin. " she said.

"Yes. And you play very well. Why did you stop" I asked.

Suddenly, a (17) expression appeared on her face and I could feel something unusual.

"I came here to see my grandmother, but now I must leave. I once played very badly. It was your listening every day that (18) me." she said.

"In fact, it was your playing (19) gave me a meaningful autumn," I answered, "Let’s be friends. "

The girl smiled, and so did I. I never heard her play again in my life. I no longer went downstairs to listen to her. Only thick leaves were left behind. But I will always remember the fine figure of the girl. She is like a (20) —so short, so bright, like a shooting star giving off so much light that makes the autumn beautiful.

8().

A.up

B.off

C.down

D.over

查看答案
微信公众账号搜索答案