寄往香港、澳门、台湾地区的印刷品专袋挂号费每袋为（）元人民币。
A.12
B.15
C.18
D.20
参考答案：B
In ancient ________, women stayed at home while men went out to labour for the family. [ ]
A. time
B. times
C. day
D. days
只用一种试剂可区别Na2SO4、MgCl2、FeCl2、Al2(SO4)3四种溶液，这种试剂是 [ ]
A．Ba(NO3)2
B．H2SO4
C．NaOH
D．AgNO3
