题干
My cousin wants to be a like Lang Lang．Because he likes playing the piano too．
A：player
B：waiter
C：musician
D：teacher
答案(点此获取答案解析）
C
My cousin wants to be a like Lang Lang．Because he likes playing the piano too．
A：player
B：waiter
C：musician
D：teacher
2SO3，如果SO2的起始浓度为2 mol/L ，2min后SO2的浓度为1.8mol/L，则用SO2的浓度变化表示的反应速率为（ ）