碘钨灯内抽真空后再充入适量和（）气体。A、氩气 B、汞蒸汽 C、氢气 D、空气

在化学王国里，数字被赋予了丰富的内涵。对下列化学用语中数字“2”的说法正确的是

①2H   ②2NH₃   ③SO₂   ④   ⑤Mg²⁺   ⑥2OH^-   ⑦H₂O[ ]

A. 表示离子个数的是⑤⑥            

B. 表示离子所带电荷数的是④⑤

C. 表示分子中原子个数的是③⑦      

D. 表示分子个数的是①②

Before, whenever we had wealth, we started discussing poverty. Why not now Why is the current politics of wealth and poverty seemingly about wealth alone Eight years ago, when Bill Clinton first ran for president, the Dow Jones average was under 3,500, yearly federal budget deficits were projected at hundreds of billions of dollars forever and beyond, and no one talked about the "permanent boom" or the "new economy." Yet in that more straitened time, Clinton made much of the importance of "not leaving a single person behind." It is possible that similar "compassionate" rhetoric might yet play a role in the general election. But it is striking how much less talk there is about the poor than there was eight years ago, when the country was economically uncertain, or in previous eras, when the country felt flush. Even last summer, when Clinton spent several days on a remarkable, Bobby Kennedy-like pilgrimage through impoverished areas from Indian reservations in South Dakota to ghetto neighborhoods in East St. Louis, the administration decided to refer to the effort not as a poverty tour but as a "new market initiative." What is happening is partly a logical, policy-driven reaction. Poverty really is lower than it has been in decades, especially for minority groups. The most attractive solution to it — a growing economy — is being applied. The people who have been totally left out of this boom often have medical, mental or other problems for which no one has an immediate solution. "The economy has sucked in anyone who has any preparation, any ability to cope with modem life," says Franklin D. Raines, the former director of the Office of Management and Budget who is now head of Fannie Mae. When he and other people who specialize in the issue talk about solutions, they talk analytically and on a long-term basis: education, development of work skills, shifts in the labor market, adjustments in welfare reform. But I think there is another force that has made this a rich era with barely visible poor people. It is the unusual social and imaginative separation between prosperous America and those still left, out... It’s simple invisibility, because of increasing geographic, occupational, and social barriers that block one group from the other’s view.

In this passage, the word "straitened" underlined in Paragraph 1 means ______.

A．difficult

B．wealthy

C．past

D．distant

某工程包括A、B、C、D、E、F、G 7个作业，各个作业的紧前作业、所需时间和所需人数见表4-2(假设每个人均能承担各个作业)。

表4-2 某工程作业情况 作业 A B C D E F G H I J 紧后作业 B、C、D、E I F G、H H I K I I — 所需时间(天) 60 45 10 20 40 18 30 15 25 35

该工程的计算工期为 (42) 月。

A．123

B．150

C．170

D．183

在荀子思想中具有科学精神的证据有（）。

A.怀疑精神

B.实证精神

C.视宇宙为自然

D.提出征服自然

关于C++与C语言关系的描述中，（）是错误的。

A.C语言是C++语言的一个子集

B.C语言与C++语言是兼容的

C.C++语言对C语言进行了一些改进

D.C++语言和C语言都是面向对象的