问题 选择题

严重烧伤的病人植皮时,要用自己的健康皮肤而不能用别人的皮肤原因是 

A.植自己的皮肤,体内不会产生相应的抗体

B.植自己的皮肤,颜色相同

C.体内不会产生免疫排斥反应

D.A和C两项均是

答案

答案:D

题目分析:免疫是指人体的一种防御功能,人体依靠这种功能识别“自己”和“非己”成分,能够及时清除自身产生的衰老、死亡和损伤细胞,破坏和排斥进入体内的抗原物质,维持人体内部环境的平衡和稳定,还可以随时监视识别和清除体内产生的异常细胞,防止肿瘤细胞的产生,在进行他人皮肤移植时,他人皮肤植入人体后,会刺激人体的免疫系统,产生免疫反应,对他人皮肤进行排斥,抑制其成活,因此移植的皮肤相当于抗原;植皮时最好移植自己的皮肤,必须移植他人的皮肤时,需要进行抗免疫治疗,否则移植不会成功,因此,严重烧伤的病人植皮时,要用自己的健康皮肤,不能用别人的皮肤,其主要原因是植自己的皮肤时体内不会产生抗体、植自己的皮肤时体内不会产生排异现象,故选D。

阅读理解

阅读理解。

      Peter wanted very much to be a soldier when he was a child. So he joined the army (军队) when

he was eighteen, and for several months he was taught how to be a good soldier. He did quite well in

everything except shooting. One day he and his friends were practicing their shooting (射击), and all

of them were doing quite well except Peter. After he had shot at the target (靶) nine times and hadn't

hit it once, the officer who was trying to teach the young soldiers to shoot said, "You are quite hopeless,

Peter. I don't waste your last bullet! Go behind that wall and shoot yourself with it!"

       Peter felt ashamed (难为情). He went behind the wall and a few seconds later, the officer and the

other soldiers heard the sound of a shot.

       "Oh, dear!" the officer said. "Has that silly man really shot himself?" He ran behind the wall as quickly

as he could, but Peter was all right."I'm sorry, sir," he said, "but I missed again."

1. Peter joined the army in order to ______?

A. be a soldier

B. be good at shooting

C. make friends

D. get a good job

2. The officer thought Peter was hopeless because ______.

A. he didn't know how to use a gun.

B. he didn't get along well with other soldier.

C. he was poor at shooting.

D. he couldn't do anything well.

3. What the officer said at the end of the first paragraph(段落) shows that ______.

A. the officer really wanted Peter to die

B. the officer was very angry with Peter

C. the officer was not a kind-hearted man

D. the officer was afraid that Peter would shoot himself

4. The officer felt ______ when he heard the sound of a shot.

A. ashamed

B. frightened

C. excited

D. disappointed (失望)

5. What happened at the end of the story?

A. Peter became a good soldier.

B. Peter killed himself behind the wall.

C. The officer was pleased with Peter in the end.

D. Peter missed the target for the tenth time.

选择题