问题 单项选择题

井巷掘进大的普通施工方法一般采用()。

A.钻眼爆破法

B.冻结法

C.钻井法

D.注浆法

答案

参考答案:A

解析:

本题考核的是普通施工法一般采用钻眼爆破的方法。在岩体上钻凿一定直径、一定深度及数量的炮眼,并在炮眼中装入炸药,靠炸药爆炸的力量破碎岩体,从而达到井巷掘进的目的,它的优点是操作简单、易于掌握、设备简单、安全可靠,可以根据要求,在岩体中钻爆出不同形状、不同深度的井筒或巷道。冻结法、钻井法、注浆法都属于特殊凿井法,是当井筒穿过不稳定含水地层,用普通凿井法无法通过时采用的特殊施工方法。

选择题
单项选择题

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, where do most Americans live

A.In the center of cities.

B.In the suburbs surrounding large cities.

C.In rural areas.

D.In small towns.