SCIENCE AND TECHNOLOGY ENGLIAH FOR MECHANICAL ENGINEERING The main question must govern the whole. And we may think of the answer to the main question as giving the proposition the thesis, the governing idea of the discussion. For instance, a historian, in answering the question Why did it occur? about the American Revolution, might come up with this answer to serve as his proposition: The causes of the American Revolution were primarily economic. "He might proceed to do a book offering a very elaborate analysis of the background of the event, but this proposition would control the whole book An example: thermomechanical treatment and precipitation hardening of a femnal alloy 热机的 ferrous manganic aluminium 铁锰铝合金SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING The main question must govern the whole. And we may think of the answer to the main question as giving the proposition, the thesis, the governing idea of the discussion. For instance, a historian, in answering the question "Why did it occur?" about the American Revolution, might come up with this answer to serve as his proposition: "The causes of the American Revolution were primarily economic." He might proceed to do a book offering a very elaborate analysis of the background of the event, but this proposition would control the whole book. An example: thermomechanical treatment and precipitation hardening of a femnal alloy. ferrous manganic aluminium 铁锰铝合金 热机的