内服吐风痰，外用灭虱杀虫的药为
A．胆矾B．常山C．瓜蒂D．藜芦
参考答案：D
She needs ________ after her mother. [ ]
A. look
B. to look
C. looking
D. looks
A．时刻t线圈中电流的瞬时值icosωt
B．线圈中电流的有效值I
C．线圈中电流的有效值I=
D．线圈消耗的电功率P
cosωt
