题目

There are two types of people in the world. Although they have equal degree of health and wealth and other comforts of life, one becomes happy and the other becomes unhappy. This arises from the different ways in which they consider things, persons, events and the resulting effects upon their minds.People who are to be happy fix their attention on the convenience of things: the pleasant parts of conversation, the well-prepared dishes, the goodness of the wine and the fine weather. They enjoy all the cheerful things. Those who are to be unhappy think and speak only of the opposite things. There如图所示电路，电源电压为9V，R1、R2的阻值均为6Ω，R3的阻值为3Ω，求：（1）当S1、S2都断开时，电流表和电压表的示数各是多少？（2）当S1、S2都闭合时，电流表和电压表的示数各是多少？