题目

如图17.4-5所示的电路中，电阻R1和R2串联接在AB两端，电压表并联接在R1两端．已知R1=10Ω，R2=20Ω，电压表示数为2.5V，则AB两端的电压U=    V。 答案：7.5  The news ________ our athletes won another gold medal was reported in yesterday’s newspaper． [　　] A．which B．whether C．what D．that