初三学生在学习电学的过程中对于由用电器和电表所组成的、看似较复杂的电路往往难以迅速、准确地作出判断.教师在教学过程中对于电表类型已知的电路图,通常采用“去表法”,即把电压表视作断路,电流表视作短路后进行判断用电器的连接,学生较容易接受.但要判断电路中未知电表的类型,对有些学生确是难题。此时仍可采用“去表法”进行分析.现举两例. In the process of learning electricity, junior high school students often have difficulty judging quickly and accurately the seemingly complicated circuits made up of electrical appliances and electricity meters. In the teaching process, teachers often use the circuit diagrams known for the types of electricity meters. The “delisting method” is to regard the voltmeter as a disconnection, and the ammeter is considered as a short-circuit to judge the connection of the electrical appliance. The students are more likely to accept it. However, judging the type of the unknown meter in the circuit is a problem for some students. At this point can still be used “to the table method” for analysis. Now give two examples.