小盟想利用一块电流表和阻值已知的电阻R0测量电阻RX的阻值．小盟选择了满足实验要求的电源、电流表A，并连接了实验电路，如图所示．小盟的实验步骤没有写完整，请你帮助小盟完成实验步骤，并写出电阻Rx的表达式．
（1）闭合开关s1，断开s2，读出电流表的示数为I2； _________ ，
（2）读出电流表的示数为I2请用，I1，I2和R0表示如RX．RX= _________ ．
（1）闭合开关s1和s2
（2）
| 阅读理解 |
Tom is a young man.He has a very big dog and he has a very small car,too.He likes playing tennis.Today he plays tennis for two hours at the club and then he wants to go home by car.His dog comes after him,but it does not jump(跳) into the same car.It jumps into the next(下一个)car. "come here, foolish dog!"Tom shouts(喊) at it ,but the dog still stays in the next car.Tom put his key into the lock(锁) of the car, but the key does not turn(转动).Then he looks at the car again.It is not his car! He is in the wrong car!And the dog is in the right car! |
| True of false(判断正T，误F) |
| ( )1.Tom has a big car. |
| ( )2.Today Tom plays tennis for two hours. |
| ( )3.Tom wants to go home by car. |
| ( )4.When Tom puts his key into the lock of the car,the key doesn't turn. |
| ( )5.In fact(事实上),Tom is in the right car. |