A.藻類大量增殖 B.溶解氧降低 C.有機(jī)物大量進(jìn)入水體 D.氮、磷營(yíng)養(yǎng)物質(zhì)濃度升高
A.普通 B.無(wú)磷
A.1/2 B.1/3 C.1/4 D.1/5