问题 单项选择题 B型题

有肠道局部免疫保护作用的是()

A.IgA抗体

B.IgD抗体

C.IgE抗体

D.IgG抗体

E.IgM抗体

答案

参考答案:A

解析:IgA抗体进入身体的黏膜表面。包括呼吸、消化、生殖等管道的黏膜,中和感染因子。IgD抗体是人类当今已知的抗体中最神秘的一种,其作用还不为人类所知。它主要出现在成熟的B淋巴细胞的表面上。可能与细胞识别有关,以便对应起相对的病原体进行免疫反应,也可能与B细胞的分化有关。IgE抗体的尾部与嗜碱细胞、肥大细胞的细胞膜结合,当抗体与抗原结合后,嗜碱细胞与肥大细胞释放组胺一类的物质促进炎症的发展,这也是引发速发型过敏反应的抗体。IgG抗体在免疫应答中起着激活补体,中和多种毒素的作用。IgM抗体是免疫应答中首先分泌的抗体。它们在与抗原结合后启动补体的级联反应,它们还把入侵者相互连接起来,聚成一堆以便于巨噬细胞的吞噬。

阅读理解

阅读理解

     George Prochnik would like the world to_put_a_sock_in_it.He makes his case in a new book, 

 Listening for Meaning in a World of Noise. Here he explains himself (using his indoor voice):

     "We've become so accustomed to noise,   there's almost a deep prejudice against the idea that

silence might be beneficial.If you tell someone to be quiet,   you sound like an old man.But it's never

been more important to find continuing quiet.Silence focuses us,   improves our health,   and is a key

to lasting peace and satisfaction."

     "We need to excite people about the sounds you start to hear if you merely quiet things down a

little.During a Japanese tea ceremony,   the smallest sounds become a kind of art-the spoons making

a light ringing sound on a bowl,   the edges of a kimono(和服)brushing against the floor."

     "Deaf people are very attentive(专注的)in almost every aspect of life.If two deaf people are

walking together,   using sign language,   they constantly watch out for each other and protect each

other by paying steady attention to the other.They are connected yet also fully aware of their

surroundings.Even deaf teenagers! We in the hearing world can learn from them.If we remove the

powerful blasts(一阵阵)of noise,   we become aware of an extraordinarily rich world around us-of

little soft sounds and the sound of footsteps,   of bird songs and ice cracking(开裂声).It's astonishing

how beautiful things sound when you can really listen."

1. What does the phrase "to put a sock in it" in Paragraph 1 probably mean?

A. to be quiet                  

B. to be colorful

C. to be full of love            

D. to be attentive to someone

2. What does Prochnik say about us?

A. We are used to quietness.

B. We have to put up with noise.

C. We do not think silence to be beneficial.

D. We do not believe lasting peace to be available.

3. Which of the following is TRUE according to Prochnik?

A. We need more sounds in our lives.

B. There is  nothing to be learned from the deaf.

C. We are not aware how rich the world around us is.

D. There is too much noise at a Japanese tea ceremony.

4. It can be inferred from the text that________.

A. we can benefit a lot from old people

B. it is a good idea to use sign language

C. there is no escape from the world of sound

D. it is possible to find how beautiful things sound

单项选择题