题目

第一节  完形填空（共10小题；每小题2分，满分20分） 阅读下面短文，掌握其大意，然后从21~30各题所给的A、B、C和D项中，选出最佳选项，并在答题卡上将该项涂黑。 In the United States there was an unusual tale telling of the daughter of a mechanic （技工）. One day while walking along the bank of a lake, the girl  21   to see 20 eggs laid by a wild goose. After some time the girl   22   the mother would not return to her eggs and she decided to take them home. There she carefully   23   the eggs in the heat of a lamp. Se如图所示的电路中，A、B端接在恒压电源上，S断开时电流表的示数2A，S闭合时电流表的示数为3A，则电阻R1与R2的阻值之比R1∶R2＝______，S断开与闭合两种情况下R1的功率之比 P1∶P1′______。