详细解释:n. 渐缩管, 缩减者, 还原剂
【化】 变径段; 变径管; 异径管; 大小头; 还原剂; 减速器; 减振器; 节流器
英语解释：
名词 reducer:
a substance capable of bringing about the reduction of another substance as it itself is oxidized; used in photography to lessen the density of a negative or print by oxidizing some of the slackened silver同义词：reducing agent, reductant