单项选择题
When the refrigeration demand is small,（）
A.the expansion valve will move toward the wide open position B.the expansion valve will move toward the closing position C.the feeler bulb will conveys the high temperature D.the superheat degree will raise
单项选择题 When the heat load begins to increase, the needle valve of an expansion valve will（）
单项选择题 One of the main purposes of refractories in a boiler furnace is to（）
单项选择题 What is the first thing you would check on taking over a watch?（）
