题目

Different countries have different customs．When you travel to another countries，please follow their customs，just as the saying goes，“             ．”     Very often people who travel to the United States forget to tip（付小费）．It is usual to tip porters who help carry your bags，taxi drivers and waiters．Waiters expect to get a 15% tip on the cost of your meal．Taxi drivers expect about the same amount．     In England，make sure to stand in line even if there are only two of you．It’s important to respect lines there．It’s a good idea to talk 在如图所示电路中，电源电压保持不变．闭合开关S，将滑动变阻器的滑片P向左移动，下列说法中正确的是（ ）A．电压表的示数不变，电流表的示数变大B．电压表的示数变大，电流表的示数变大C．电流表的示数与电流表的示数同时变大D．电流表的示数与电流表的示数同时变小