pstn 基本解释 public switched telephone network,公共交换电话网络 同首字母单词 p [pi:] pa [pɑː] paal [pɑːl] paba pablum ['pæbləm] pabouche [pɑː'buːʃ] pabulum ['pæbjʊləm] pabx pac [pæk] paca ['pækə] pacchionian pace [peɪs]