当机组处于冷态、温态、热态、极热态启动时，锅炉如何控制各状态启动冲转参数？
参考答案：
各状态冲转参数见表2—3。
— How was your recent trip to Sichuan?
— I've never had ________ one before. [ ]
A. a pleasant
B. a more pleasant
C. a most pleasant
D. the most pleasant
体表没有角质硬鳞的鱼类品种是鲳鱼、鲅鱼、带鱼、（）。
never had ________ one before. [ ]