A new eight-kilometer road is under construction that links the port area with motorway system. It is expected to carry 20,000 trucks and cars a day, which greatly reduces the overcrowded traffic in the center of the city. As part of the project, two four-kilometer road tunnels are being built below the central area of the city, one for traffic to the north and the other for the traffic to the south. The two tunnels are about 20 meters below the surface and are 12 meters wide, providing for two lanes of traffic in each direction.
In the upper part of the tunnel two air-conditioning pipes remove the waste gas of trucks and cars and keep the quality of air inside the tunnel. The lighting is at the top of the tunnel, practically at its highest point. There will also be electric signs at frequent intervals. They show traffic conditions ahead and can be seen clearly by drivers. The wall is made up of four main elements, which include a waterproofing covering and, on the inside of the tunnel, a concrete lining（混凝土衬砌）.
Each tunnel is roughly round and the lower part of the tunnel is somewhat flat. The surface of the road lies on the base, which is made of concrete and steel. The drainage system, just below the road surface on one side, removes any extra liquid, particularly water. In the event of fire, the fire main, which is made of steel, pipes water to many fire hydrant stations at regular intervals along the length of the tunnel. The fire main is at the side of the tunnel and at the level of the road surface. Other systems in the tunnel will include emergency phones.
72. Each of the tunnels under construction is .
A. eight kilometers long and twenty meters wide B. eight kilometers long and six meters wide
C. four kilometers long and twenty meters wide D. four kilometers long and six meters wide
73. Which part of the tunnel in the diagram is used to pipe out extra water?
A. 1 B. 3 C. 5 D 6
74. Driving in the tunnel, one can know the traffic conditions ahead through .
A. the lights B. the electric signs
C. the trucks and the cars D. the emergency phones
75. The passage is mainly about .
A. the construction of a road B. the design of a road
C. the construction of two tunnels D.the design of two tunnels 72--75 DCBD
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(答案→)72--75 DCBD
解析：
72．解析：这是一道细节推断题。从第一段“As part of the project, two four-kilometer road tunnels are being built”可知，tunnels长4公里；从“The two tunnels are about 20 metres below the surface and are 12 metres wide”可知，两个隧道宽12米，因此1个隧道宽6米。
73．解析：这是一道判断题。本题问的是“排除多余的水的管道在隧道的什么部分”。从第三段“The drainage system, just below the road surface on one side, removes any extra liquid, particularly water.”可知排水系统正好在路表面一边的下方，对照剖面图，5符合这个位置。
74．解析：这是一道细节推断题。从第二段“There will also be electronic signs at frequent intervals. They show traffic conditions ahead”可知电子告示的作用是显示交通状况，因此选B。
75．解析：这是一道主旨题。文章主要讲的是两个隧道，因此首先排除A、B。文中讲到的是隧道的内部构造，因此C“两个隧道的建设”也不对。