【英语时差8,16】为什么要给汽车换油？（上）

How often do you change the air in your tires? How about your brake and radiator¹ fluids? You may need to fill them up or change them once in a while, but you don’t have to change them the way you have to change your oil. You should change the water in your radiator because it gets dirty, and that’s one of the reasons to change your oil as well. But there’s another, more significant reason that old oil doesn’t work as well as new oil. Inside your car’s engine, metal parts are constantly sliding across each other at extremely high speeds. The friction² of metal against metal at that speed could generate enough heat to destroy the engine — if there weren’t oil to lubricate the metal parts and help them slide more easily. The long molecules³ of oil work their way between the metal parts so that moving metal parts never really touch each other. But those long chains don’t last forever.

1 radiator   

n.暖气片，散热器

参考例句：

• The two ends of the pipeline are connected with the radiator.管道的两端与暖气片相连接。
• Top up the radiator before making a long journey.在长途旅行前加满散热器。

2 friction   

n.摩擦，摩擦力

参考例句：

• When Joan returned to work,the friction between them increased.琼回来工作后，他们之间的摩擦加剧了。
• Friction acts on moving bodies and brings them to a stop.摩擦力作用于运动着的物体，并使其停止。

3 molecules   

分子( molecule的名词复数 )

参考例句：

• The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
• Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里，大分子裂变为小分子。