向下列各物质的水溶液中滴加稀硫酸和MgCl2溶液时，均有白色沉淀的是[ ]
A．BaCl2
B．Ba(OH)2
C．Na2CO3
D．KOH
答案：B
--Excuse me. Could you tell me to Xi’an Expo?
--Take No.231 to get there.
A．which bus should I take
B．how far is it
C．which bus I should take
D．how far it is
车床的三星齿轮的作用是什么？
