由无药理活性的中性物质制成的、外形似药的制剂属安慰剂()
参考答案：对
Mrs. King has ____ China for over three years. [ ]
A. gone to
B. been to
C. come to
D. been in
出水量呈周期性变化的澄清池是：（）
A.悬浮澄清池
B.机械加速澄清池
C.水力循环澄清池
D.脉冲澄清池
