I often go to a movie my good friends.[ ]
A. on
B. and
C. with
D. in
答案：C
如图所示电路，变阻器R1最大阻值为4Ω,此时它的有效阻值为2Ω，定值电阻R2=6Ω，电源内阻r=1Ω，当开关闭合时，电源消耗的总功率为16W，输出功率为12W，此时电灯恰好正常发光，求：
小题1:电源的热功率；
小题2:电源的电动势；
小题3:电灯的电阻。
Which of the following statements is NOT true of the passage
A．International trade has become an important part of national development.
B．Summit talks will be held to discuss problems in international trade.
C．Developing countries benefit more from international trade than development aid.
D．The Doha Development Agenda has made development its pivotal concern.
