短語詞組短語frequency cumulative distribution curve 頻率累積分布曲線frequency -distribution curve 頻率分布曲線Bellshaped frequency distribution curve 正態(tài)分布hydrologic frequency distribution curve 水文頻率分布曲線size -frequency distribution curve of particle [土壤]粒徑頻率分配曲線curve frequency distribution 頻率分布曲線distribution of frequency curve 頻率曲線分布 返回 frequency distribution curve