他们必须保持柴油有一定的温度，因为发动机要随时启动。
They keep the oil heated all the time because any minute they may need to start the engines.
因为发动机没有阀门，它不需要任何凸轮轴、起阀器等。
Since the engine has no valves, it doesn't need any camshaft, valve lifters and so on.
因为发动机需要空气才能工作，所以也不会有轿车或卡车。
There would be no cars or trucks, since motors need air in order to work.
应用推荐