偏心分层配水管柱按封隔器类型可分为（）配水管柱。
A、洗井式
B、不可洗井式
C、锚定式
D、细分式
参考答案：A, B
—Why are you so depressed?
—I _____ my MP4 player on the bus. [ ]
A. had lost
B. am lost
C. have lost
D. was lost
单因素试验
