How old your father?[ ]
A. am
B. is
C. are
答案：B
如图所示,理想变压器的输入端接220 V的正弦交流电,副线圈上接有灯泡L和电热器R,开始时开关S断开.当S接通时,以下说法中正确的是( )
A．副线圈M、N的两端输出电压减小
B．副线圈M、N的两端输出电压增大
C．灯泡L的电功率不变
D．原线圈中的电流增大
One day we will manage to ______ the world ______ this terrible disease—cancer.
A．get rid; of
B．refer; to
C．rid; of
D．treat; to
