可用来鉴别己烯、四氯化碳、苯的试剂是
A．硫酸
B．溴水
C．乙醇
D．盐酸
答案：B
溴水使己烯褪色，和四氯化碳、苯都萃取，一个溴在下层一个溴在上层。
---Where did you see the sponsor, Madame?
---It was in the supermarket __________I was doing some shopping with my husband.
A．that
B．where
C．which
D．when
DCS控制的意义是什么？
