已知正实数a的两个平方根分别是b、c，请计算代数式a+b+c+bc的值。

警察的政治 * * 职能和社会管理职能，构成了警察的基本职能。( )

How many _________ are there in your class?[ ]

A. computer         

B. computers              

C. computre         

D. computeres

Most Americans enjoy moving from place to place. For example, they often drive their cars 120 to 160 kilometers away just to have dinner with a friend or even fly to Europe just for watching a football match. In some states only one person in five lives in a place for more than five years. One may be born in one city, and go to school in another. He may finish his middle school in two or three cities, and then attend a college far across the country. When he has entered business, he may possibly move from job to job. Moving from one job to another, which is called “job-hopping”, is a very common practice in the United States. Job-hopping is good to workers, because every change of a job gives them a chance to move up to a higher position and to get better pay. And job-hopping also gives bosses the chance to get new ideas and skills that different people bring to their companies and factories.

1. According to this passage, Americans often travel_______.

A. in order to have dinner with their friends

B. in order to watch football matches

C. to enjoy themselves

D. in order to find a new job

2. In some places in America, ________ for more than five years.

A. most people stay in one place

B. about 20% of the people live in one place

C. the owners of houses stay in one place

D. the owners of five house stay in one place

3. In the USA, job-hopping_______.

A. has become the custom (习惯)

B. has helped young people to attend to college

C. has helped students to enter business

D. has helped worker in traveling

4. The writer thinks________.

A. job-hopping does good either to workers or to the bosses

B. job-hopping does good neither to the workers nor to the bosses

C. little of the job-hopping

D. highly of the job-hopping

物权的保护应当采取( )的方式。

A．因物权的归属、内容发生争议的，利害关系人可以请求确认权利

B．无权占有不动产或者动产的，权利人可以请求返还原物

C．因合法建造、拆除房屋等事实行为设立或者消灭物权的，自事实行为成就时发生效力

D．侵害物权，造成权利人损害的，权利人可以请求损害赔偿，也可以请求承担其他民事责任

E．造成不动产或者动产毁损的，权利人可以请求修理、重作、更换或者恢复原状

特种蛋白免疫分析仪是基于抗原一抗体反应原理，不溶性免疫复合物可使溶液浊度改变，再通过浊度检测标本中微量物质的分析方法。

产生伪浊度的主要因素（）

A.抗体的非特异性交叉反应性

B.增浊剂浓度过低

C.反应时间不合适

D.仪器故障

E.抗原过剩