How much percent of impurities are enough to make domestic sewage unfit for humans?
A. 0.1 percent
B. 1 percent
C. 5 percent
D. 10 percent
Answer:A
How much percent of impurities are enough to make domestic sewage unfit for humans?
A. 0.1 percent B. 1 percent C. 5 percent D. 10 percent