搜题请搜索小程序“爱下问搜题”
问题 单项选择题

阅读以下文字，完成以下问题。
艾滋病实际上不是一种疾病，而是由人体免疫功能障碍导致的一组征候群。也就是说，最终导致艾滋病患者死亡的并不是艾滋病病毒，而是那些通常在人体免疫系统功能正常时不会发生的由各种病毒、细菌、真菌、寄生虫等机会性感染所导致的疾病和肿瘤。人体免疫系统似乎对艾滋病病毒失去了防御能力，致使人体一旦感染艾滋病病毒，病毒便长驱直入，直接攻击免疫系统本身。
艾滋病病毒如何感染给人以及后来如何发展为艾滋病患者的机理目前还不是十分清楚。但是一般认为，艾滋病病毒直接感染人体的CD4T淋巴细胞、巨噬细胞和神经胶质细胞，病毒借助于外膜糖蛋白进入这些细胞。进入细胞内即释放RNA，并在逆转录酶的作用下转录成DNA，并插入宿主细胞的染色体DNA中，从此就长期地“躲”在那里。此后，病毒DNA被宿主细胞的 RNA转录为mRNA，并翻译“生产”病毒所需的结构蛋白。病毒RNA与结构蛋白在细胞膜上重新装配新的病毒颗粒，通过芽生而释放。在感染的初期，当机体内出现针对艾滋病病毒的特异性细胞毒性淋马细胞后，体内的病毒水平开始下降，这种免疫反应不能消除艾滋病病毒感染，但它可以使病毒在复制和清除之间形成一种相对平衡的稳定状态，因而没有造成严重的T细胞、巨噬细胞损伤和耗竭，并在血清抗体变，阳性后的相对时期处于长期无症状病毒携带期或持续性全身性淋巴结肿大综合症阶段。人体的免疫系统同病毒就这样进行着长时间的较量，终于在其他因素的[ ]刺激下，T细胞和巨噬细胞内的艾滋病病毒开始大量复制，打破了这种平衡，使一部分细胞发生凋亡。随着时间的推移，在没有任何有效治疗的情况下，人体免疫系统由于持续作战，CD4T淋巴细胞被不断的感染和杀伤，出现了“寡不敌众“、无力”搞敌“的局面，于是那些在人体免疫系统功能政党情况下并不致病的微生物或潜伏在体内陆 的微生物便趁虚而入，严惩的机会性感染和肿瘤发生了，最生导致艾滋病患者死亡。其中一部分人在半年到2年内即可以从无症状期发展到艾滋病患者。
此外，艾滋病病毒可致T细胞成熟障碍以及抗原辅佐细胞功能丧失，造成免疫系统功能障碍、自身免疫性损害等，使T细胞迅速减少并最终耗竭。由于T细胞在免疫网络中起中心作用，导致整个免疫系统崩溃，感染者迅速发展为艾滋病患者。

下列对“人体免疫系统”这一概念的理解，错误的一项是( )。

A．人体的免疫系统主要作用是抵御病毒入侵，其功能正常时，人体不会发生由一般病毒、细菌、真菌、寄生虫等机会性感染所导致的疾病和肿瘤

B．人体一旦感染艾滋病病毒，人体免疫系统的防御功能就会丧失，病毒便长驱直入，直接攻击免疫系统本身

C．在感染的初期，免疫系统开始发挥作用，机体产生的免疫反应使病毒在复制和清除之间形成一种相对平衡的稳定状态

D．免疫系统的崩溃是以T细胞的迅速减少并最终耗竭为标志的

答案

参考答案：B

解析：解析：B项“防御功能就会丧失”不正确。

阅读理解

阅读理解

                                     Moving out, moving back

       In the countries all over the world, people are leaving the countryside in large numbers to find jobs in

the cities. They leave because the countryside is much poorer than the city, and often there isn't much work there. Services such as hospital and transport are usually much better in cities than they are in the country. They hope that their lives will improve when they move to the city.

       But in the big cities of Europe and America-London, Paris, New York, people are moving out of

the city. These are usually families who have some money, and want to live a quieter life. They are tired of

the noise and the dirt of the city, tired of the crowded streets, crowded trains and buses. They don't want

to sit in traffic any more. They want a house with a garden, and clean air that isn't polluted.

       So they move out. Some don't go very far, just a little way out of the city, to the towns near the cities, other people move to the real countryside with sheep and cows and green fields!

       There, they start new lives and try to make new friends.

       Not all those who move from the city to the countryside are happy. After two or three years, many

people who have done this feel that it was a big mistake. They don't make so much money and there isn't much to do. Country people are very different and aren't always very friendly.

       As a result, quite a lot of people who have moved to the countryside move back to the city. "It's

wonderful to see crowded in the streets and cinema lights," they say, "I'm so glad back in the city !"

1. Is there often much work to do in the countryside?

                                                                                   

2. What kind of families are moving out of the city?

                                                                                   

3. What are they tired of about the city? (答两点即可)

                                                                                    

4. What do they think of the people in the countryside?

                                                                                    

5. What can we learn from the sentences "It's wonderful to see crowded in the streets and cinema lights" ?

                                                                                    

查看答案
单项选择题

《国务院关于印发完善城镇社会保障体系试点方案的通知》中规定，城镇企业职工基本养老保险个人账户规模由本人缴费工资的11%调整为（）。

A.6%

B.7%

C.8%

D.10%
查看答案