软水器再生后出水氯离子含量不得大于进水氯离子含量的1.1倍。（）
参考答案：对
Heavy objects and light objects fall at the same speed ________ air holds them back.[ ]
A. so that
B. if
C. unless
D. although
机组开车时，应确认PIC204有（）开度。
A.全关
B.20%
C.40%
D.50%
