Tom and Mike are good friends. They are kind to children. They want to find summer jobs. One day Tom tells Mike that Beidaihe Kids Summer Camp needs help with sports, music and computers. They are both very glad to hear(听说) this. Tom can play basketball and volleyball, and he can swim, too. Mike can play the violin, the trumpet, the drums and the guitar. Tom and Mike like computers very much. Can they join the Summer Camp?
根据短文内容，选择正确答案（10分）
小题1:Tom and Mike want to _________.
A、help with sports, music and computers
B、be good with children
C、join the Summer Camp
小题2:What does the Summer Camp need help with?
A、Flying kites.
B、Sports, music and computers.
C、Making cakes.
小题3:Tom can play____________
A、balls B、computer games C、music
小题4:Mike can play__________
A、the drums B、volleyball C、basketball
小题5:What do Tom and Mike both like?
A、Football. B、Computers. C、Swimming.
，当开关S断开时，电流表的读数为I1=0.6A；当开关S闭合时，电
流表的读数为I2=0.84A，求电源的电动势E和内电阻r。