浮动床与一般固定床相比（）。
A、需定期体外清洗
B、再生剂消耗高、出水品质差
C、再生时树脂容易乱层
D、操作复杂
参考答案：A
叶丝填充值低的原因有那些？
They would not allow him _____ across the enemy line. [ ]
A. to risk going
B. risking to go
C. for risk to go
D. risk going
