哪一钟不是脂溶性维生素（）
A.维生素A
B.维生素D
C.维生素E
D.维生素B
参考答案：D
The fellow left without a word as if ________．
A．never to return
B．never returning
C．he had never returned
D．he would never be returning
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
