—Can you work put the physics problem?

—Sorry, I can _________ understand its mean­ing.

A．almost

B．quite

C．nearly

D．hardly

污水排放指标中三级的COD数值正确的是（）。

A、COD≤300mg/L

B、COD≤650mg/L

C、COD≤400mg/L

D、COD≤500mg/L