化学需氧量(COD)
是指水样在规定条件下用氧化剂处理时,其溶解性或悬浮性物质消耗该氧化剂的量。
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
免费的网站请分享给朋友吧