浓缩倍数偏高时一般采取增加旁滤系统的反洗频次或（）的处理方法。
参考答案：排污
As soon as the crew(船员) were attacked, the police______ to look into the matter.
A．set down
B．set out
C．set about
D．set up
船艉垂线指通过船艉柱后缘和夏季满载水线交点的垂线。如没有船艉柱的船舶，则以舵杆中心为船艉垂线。（）
