注水泵站投产试运后,各种工艺指标必须满足要求,污水中含油应()。
A、≦100mg/L
B、≦80mg/L
C、≦50mg/L
D、≦30mg/L
参考答案:D
下列能使蒸发变慢的措施是[ ]
A.用瓶子装酒精时一定要加盖
B.夏天,人们使用电风扇扇风
C.把湿衣服展开晾在通风向阳处
D.用塑料袋包装蔬菜放入冰箱内
Something that oligopolists will try to engage in with another firm in setting a higher price is called :()
A. high economic profits.
B. prisoner's dilemma.
C. collusion.