concentrationn.集中；专心；浓度concentration on sth专心； 集中精力Concentration of tin锡concentration effect浓度效应,浓化效应concentration period集中期concentration switch汇总开关concentration butter[医] 浓缩试验(检肾机能)concentration ratios市场集中度concentration cycled浓度切换concentration fields浓度场concentration centre浓集中心