4) 第一个电极叫发射极，等二个叫基极，而第三个叫集电集。

The first is called the emitter. The second is the base and the third the collector.

5) 石油是液体燃料的最大来源，虽然人们作出许多努力去研制合成燃料并继续使用固体燃料，石油产品的世界消耗量，目前仍超过了1940年的四倍左右。

Petroleum is the largest source of liquid fuel. In spite of attempts to develop synthetic fuels,and to continue using solid fuels, world consumption of petroleum products is about four times greater now than in 1940.

6) 当车辆在路上行驶时，其重量经车轮传递给车下的路面，刚性路面的功能，与柔性沥青路面相反，可通过路基分散动压力和施加在动压力上的任何附加压力。

When a vechicle passes over a road，its weight is transmitted through the wheels on to the pavement beneath it. The function of the rigid pavement，as opposed to the flexible tarred pavement, is to distribute the dynamic stresses，and any additional stresses which may be superimposed on them through the sub-grade.

7) 在软木塞上钻ー个小孔，将ー根玻璃管插入软木塞的孔中。

Make a hole through the cork. Push a tube through the hole in the cork.

8) 因此，关于阀的开启有效行程应当是指气包压力开始下降（即气箱扳力明显上升）的A’点到气包压カ开始趋于平稳的B’点阀所经历的行程。

Therefore, the effective stroke of the valve during opening should be the distance the valve travels from point A’to point B'. At point A' the pressure in the air tank begins to fall (that is，the pressure in the clearance of the upper part of the flask begins to rise obviously). At point B' the pressure in the air tank begins to be steady.

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