对立案检查的案件，案件调查的时限为（）个月，必要时可延长1个月。
A.1
B.2
C.3
D.4
参考答案：C
Environment-friendly Olympics requires Beijing to improve its environment, turning it into an ecology-friendly city.
A．eventually
B．specially
C．absolutely
D．traditionally
COD浓度高，表明水体受有机物污染较为严重。（）
