稀释与接种法测定水中BOD，时，如水样为含难降解物质的工业废水，可使用（）的稀释水进行稀释。
参考答案：经驯化的微生物接种
-- Mr. White, will you please teach me how to perform pair skating today?
-- . You have to practise single skating well first.
A．Two heads are better than one.
B．Think twice before you do.
C．Learn to walk before you run.
D．One today is worth two tomorrows.
引起大气运动的根本原因是（）
A、地球自转
B、地球公转
C、太阳辐射能在不同纬度分布不均
D、海陆热力性质差异
