题目

小红同学在“测量小灯泡电功率”的实验中，选取额定电压为2.5 V的小灯泡，电压恒为3 V的电源、电流表、电压表、开关、导线若干，另有三种规格的滑动变阻器可供选择：R1(10 Ω 1 A)，R2(20 Ω 0.5 A)，R3(50 Ω 0.2 A)，按如图甲所示的电路图进行实验．(1)请将图乙中的实物电路连接完整(要求：滑动变阻器的滑片向左移动时小灯泡变亮)____________．(2)闭合开关，调节滑片的位置，当小灯泡两端电压为2.5 V时，电流表的示数如图丙所示，则小灯泡的额定功率为_____A Two-way Student Exchange 　　This year 1 twenty-three hundred teenagers from all over the world will spend about ten months in U. S. 2 . They will attend U. S, schools, meet U. S. teenagers, and form 3 of the real America. At the same time, about thirteen hundred American teenagers will go to other countries to learn new 4 and gain a new understanding of the rest of the world. 　　Here is a two-way student exchange in action. Fred, nineteen, spent last year in Germany with George's family. 5 , George's son Mike spent a year in Fred's home in America. 　　Fred, a lively young man; knew little German when he arrived, but after two months' study, the language began to come to him. School was completely different from what he had expected－much 6 . Students rose respectfully when the teacher entered the room. They took fourteen subjects 7 the six that are usual in the United States：There were almost no 8 activities. 　　Family life, too, was different. The father's word was 9 , and all activities were around the family rather than the individual. Fred found the food too simple at first. 10 , he missed having a car. 　　“Back home, you 11 some friends in a car and go out and have a good time. In Germany, you walk, but you soon learn to like it.” 　　At the same time, in America, Mike, a friendly 12 boy, was also forming his idea. “I suppose I should criticize American school,” he says. “It is far too easy by our 13 . But I have to say that I like it very much. In Germany we do nothing but 14 . Here we take part in many outside activities. I think that maybe your schools are better in training for 15. There ought to be some middle ground between the two.” 1． [　　] A．nearB．some C．anyD．a number of 2． [　　] A．homesB．schools C．townsD．vacation 3． [　　] A．opinionsB．impressions C．expressionsD．habits 4． [　　] A．nationalitiesB．computers C．scienceD．languages 5． [　　] A．In turnB．At once C．InsteadD．As a result 6． [　　] A．more interestingB．easier C．harderD．more comfortable 7． [　　] A．more thanB．less than C．fewer thanD．instead of 8． [　　] A．politicalB．indoors C．outsideD．inside 9． [　　] A．rightB．law C．truthD．power 10． [　　] A．InsteadB．Also C．ThereforeD．However 11． [　　] A．get onB．pick up C．put onD．take away 12． [　　] A．AmericanB．English C．GermanD．French 13． [　　] A．meansB．way C．countryD．level 14． [　　] A．studyB．look for jobs C．read booksD．learn foreign language 15． [　　] A．officersB．politicians C．citizensD．athletes