cough 为什么加s
他是可数名词，复数要加s 复数 coughs 第三人称单数 coughs 现在分词 coughing 过去式 coughed 过去分词coughed whooping cough 百日咳 cough up 勉强拿出；勉强给出 cough mixture 止咳药水；止咳剂 cough ｄｒｏｐ 止咳糖；止咳片 dry cough 干咳 hacking cough 短促频繁的干咳 cough something up 勉强拿出；勉强给出 smoker's cough...