托运（）等时，必须派人押运。
A.金银珠宝、货币证券
B.档案材料
C.蛇、蝎子、蜈蚣、蜂
D.妨碍公共卫生和安全的物品
参考答案：A
His father looks young, but _____ fact he is _____.
A．in; in the forties
B．in; in his forties
C．in the; in the forties
D．in; in his forty
A．若磁场正在增强，则电场能正在减少，电容器上极板带正电
B．若磁场正在减弱，则电场能正在增强，电容器上极板带正电
C．振荡电流的变化周期为：2π
D．电场能量的变化周期为：π
