关于x2-x-n=0没有实数根，则y=x2-x-n的图象的顶点在（ ） A．第一象

The physicians in a hospital form the core of the medical staff. But they couldn’t provide effective medical care to their patients without the help of numerous other medical employees. From the viewpoint of the patients, the nursing staff is particularly important. Nurses are usually in close contact with patients as long as they are in the hospital.

A nurse does not study for as many years as a doctor. However, each must be equally dedicated. Caring tot sick persons requires a great deal of patience and concern. Most nurses work long days, and they often must work at odd hours or during the night.

Under the supervision of the head nurse, the nursing staff must provide nursing services on 24-hour basis and attend to patients’ needs. This responsibility continues around the clock, and so nurses must work in shifts. A shift is a period of duty, usually eight in length. The nurses on the ward rotate their shifts. All of them work out of a central area on the ward called the nurses’ station.

A nurse must always be alert. She can never afford to be careless. This is true in all nursing situation, but it is especially true in the intensive care unit. Patients under intensive care duty have one of the most demanding jobs in the hospital.

Serving as a nurse can be a very. rewarding job. But it is not an easy one. Not every person is suited to become a nurse. Only very dedicated people have chosen nursing as a profession.

Why don’t nurses study for as many years as doctors（）

A．Most nurses work long days.

B．They don’t treat patients for illness and injury.

C．Caring for sick patients requires patience and concern.

D．They are not dedicated.

中华文明对世界其他民族有很大的吸引力。下列史实能证明这一结论的是 （  ）

①玄奘西游               ②回族的形成   

③日本派遣唐使到中国学习 ④土尔扈特回归祖国                   

A．①②

B．①②③

C．②③④

D．②③

经拥有本物业20％及以上的业主提议，业主委员会应当组织召开（）。

A.业主大会临时会议

B.年度会议

C.首次业主大会

D.业主年度会议

下列关于实验现象的描述，正确的是（　　）

A．镁条在空气中燃烧，发出白色火焰，生成白色粉末

B．细铁丝在氧气里剧烈燃烧，火星四射，放出热量，生成黑色固体物质

C．加热试管里的氢氧化铜蓝色沉淀，蓝色沉淀没有变化

D．蜡烛在氧气里燃烧比在空气里燃烧得更旺，发出红光

The percentage of immigrants (including those unlawfully present) in the United States has been creeping upward for years. At 12.6 percent, it is now higher than at any point since the mid 1920s. We are not about to go back to the days when Congress openly worried about inferior races polluting America’s bloodstream. But once again we are wondering whether we have too many of the wrong sort of newcomers. Their loudest cites argue that the new wave of immigrants cannot, and indeed do not want to, fit in as previous generations did.

We now know that these racist views were wrong. In time, Italians, Romanians and members of other so called inferior races became exemplary Americans and contributed greatly, in ways too numerous to detail, to the building of this magnificent nation. There is no reason why these new immigrants should not have the same success.

Although children of Mexican immigrants do better, in terms of educational and professional attainment, than their parents, UCLA sociologist Edward Telles has found that the gains don’t continue. Indeed, the fourth generation is marginally worse off than the third. James Jackson, of the University of Michigan, has found a similar rend among black Caribbean immigrants, Telles fears that Mexican Americans may be fated to follow in the footsteps of American blacks—that large parts of the community may become mired in a seemingly state of poverty and underachievement. Like African Americans, Mexican Americans are increasingly relegated to (降入) segregated, substandard schools, and their dropout rate is the highest for any ethnic group in the country.

We have learned much about the foolish idea of excluding people on the presumption of the ethnic/racial inferiority. But what we have not yet learned is how to make the process of Americanization work for all. I am not talking about requiring people to learn English or to adopt American ways; those things happen pretty much on their own, but as arguments about immigration hear up the campaign trail, we also ought to ask some broader question about assimilation, about how to ensure that people, once outsiders, don’t forever remain marginalized within these shores.

That is a much larger question than what should happen with undocumented workers, or how best to secure the border, and it is one that affects not only newcomers but groups that have been here for generations. It will have more impact on our future than where we decide to set the admissions bar for the latest ware of would be Americans. And it would be nice if we finally got the answer right.

What does Edward Telles research say about Mexican Americans（）

A．They may slowly improve from generation to generation.

B．They will do better in terms of educational attainment.

C．They will melt into the African American community.

D．They may forever remain poor and underachieving.