短語詞組短語features selecting and extracting 特征選取mixed features extracting method 混郃特征提取morphological features extracting 形態(tài)特征提取features extracting techniques 特征提取features extracting and selecting 特征提取與選擇extracting features 特征提取combined extracting features 聯(lián)郃提取特征extracting irregular features 不槼則特征提取extracting of features 特征提取 返回 features extracting