一、境空题1一如图1所示，若使电路中自由电子的运动方向如箭头所示，则金属导线的线头a应接在电源的极上，线头必应接在电源的极上．2．如图2所示，若要使灯L；发光而L。不发光，应将开关＿＿＿＿＿闭会、＿断开；要使灯L。发光而L；不发光，则应将开关＿．闭合、．＿＿断开； 1. As shown in Figure 1, if the direction of the free electrons in the circuit is indicated by an arrow, the wire a of the metal wire should be connected to the pole of the power supply. The wire must be connected to the pole of the power supply. . 2. As shown in Figure 2, to make the lamp L; Do not light, switch _____ should be closed, _ disconnect; to make the lamp L. Luminous and L; no light, the switch should be _. closure,. __disconnect;