通过鼓风式除碳器，通常可将水中的二氧化碳含量降至（）mg/L以下。
A.1
B.2
C.3
D.5
参考答案：D
—Is Betty _____ music now?
—Yes, _____. [ ]
A. listen to; she is
B. listening to; she is
C. listening to; she isn't
D. listen; she isn't
对方的站位和（）会显示其投篮的类型。
A.形体动作
B.面部表情
C.言语信息
D.动作方式
