题目

如图所示的甲、乙两个电路，闭合开关后都会使得保险丝熔断。关于保险丝熔断的原因，下列说法正确的是（ ） A．甲图是由于灯泡被短路    B．甲图是由于灯泡被断路    C．乙图是由于电路总电阻太大，功率太大       D．乙图是由于电路总电阻太小，功率太小 答案：A。 【分析】电路中电流过大，保险丝熔断的原因有：电路发生短路和电路中用电器的总功率过大。 【解答】解：A、B、甲图中，闭合开关，电流从火线经保险丝、金属丝回到零线，造成电路短路；同时灯泡也被短路，灯泡中没有电流通过，不发光，保险丝烧断。故A正确、B不正确； C、D、乙图中，各用Watching movies for your summer Pirates of the Caribbean: Dead Man’s Chest 加勒比海盗：聚魂棺    Captain Jack Sparrow again appears on the screen. This time, he finds himself in a heavy debt(债) to Davy Jones. The only way to get out of it is to find the Dead Man’s Chest. He asks his old fiends for help and they start out to the sea. Garfield: A Tale of Two Kitties  加菲猫: 双猫记    Hello, Garfield will meet you again on the screen. This time, America’s favourite cat Garfield travels to London. Garfield gets lost on the way. However, he enjoys his new life in his new home. But danger is near him… Superman Returns   超人归来    How exciting it is to see Superman on the screen again! Like before, he is again saving the world. But his enemy, Lax Luther, is still planning to kill him so that he can control the world. 1.What does the underlined word “it” refer to? A. His debt.      B. His old friend.     C. His new life. D. The Dead Man’s Chest. 2.Which of the following doesn’t happen to Garfield? A. He gets lost.                       B. He has his new home and enjoys his new life. C. Danger is waiting for him.            D. He is in a heavy debt. 3.Why does Lax Luther plan to kill Superman? A. Because he wants to save the world.    B. Because he wants to enjoy his new life. C. Because he wants to control the world.  D. Because he wants to control Superman.