一、填空题1．内能的应用，一是利用内能直接_____，二是利用内能对外_____。2．热机是把_____能转化为_____能的机器，汽油机和柴油机统称为＿机，因为它们都是让燃料在＿里燃烧而工作的．3·汽油机的工作过程是由_____＿．、＿＿和＿＿＿冲程组成一个工作循环的，其中＿冲程 First, fill in the blank 1. The application of internal energy, the first is the use of internal energy directly _____, the second is the use of internal energy to the external _____. 2. Heat engines are machines that convert _____ into _____ energy, gasoline engines and diesel engines are collectively referred to as _machines because they all work by burning fuel in the air. 3. The working process of the gasoline engine is ______. The __ and __ strokes constitute a working cycle, where _ strokes