脊髓髓外硬膜下肿瘤的临床表现为（） A.早期神经根性疼痛 B.进行性病程 C.腰椎穿

下列哪项不是ADHD注意缺陷型的诊断标准（）

A.在学习、工作或者其他活动中常难以在细节问题上集中精力或常犯粗心大意的错误

B.在学习、工作或娱乐活动中难以保持注意力集中

C.讲话喋喋不休、多嘴多舌

D.对构思筹划性作业和工作常感到很困难

E.在与他人谈话时常显得心不在焉、似听非听

确定空调房间围护结构的传热系数时，需要考虑的因素有______。

A．室内外温差、恒温精度

B．建筑物的用途和空调的类别

C．空调制冷系统的投资和运行费用

D．空调新风量

内蒙古自治区现辖的三个盟分别是（）、锡林郭勒盟、阿拉善盟。

在表达式x-y中，“-”是作为非成员函数重载的运算符。若使用显式的函数调用代替直接使用运算符“-”，这个表达式还可以表示为

A．x．operator-(y)

B．operator-(y，x)

C．y operator-(x)

D．operator-(x，y)

The fact that most Americans live in urban areas does not mean that they reside in the center of large cities. In fact, more Americans live in the suburbs of large metropolitan areas than in the cities themselves.

The Bureau of the Census regards any area with more than 2,500 people as an urban area, and does not consider boundaries of cities and suburbs.

According to the Bureau, the political boundaries are less significant than the social and economic relationships and the transportation and communication systems that integrate a locale. The term used by the Bureau for an integrated metropolis is an MSA, which stands for Metropolitan Statistical Area. In general, an MSA is any area that contains a city and its surrounding suburbs and has a total population of 50,000 or more.At the present time, the Bureau reports more than 280 MSAs, which together account for 75 percent of the US population. In addition, the Bureau recognizes 18 megapolises, that is, continuous adjacent metropolitan areas. One of the most obvious megapolises includes a chain of hundreds of cities and suburbs across 10 states on the East Coast from Massachusetts to Virginia, including Boston, New York, and Washington, D.C. In the Eastern Corridor, as it is called, a population of 45 million inhabitants is concentrated. Another megapolis that is growing rapidly is the California coast from San Francisco through Los Angeles to San Diego.

According to the passage, what is a megapolis().

A. One of the 10 largest cities in the United States.

B. One of the 18 largest cities in the United States.

C. One of thel00 cities between Boston and Washington.

D. Any number of continuous adjacent cities and suburbs.