解释下列句中加点字词的古义和今义
⑴今之众人，其下圣人也亦远矣。
                                                                           
⑵古之学者必有师。
                                                                             ⑶蚓无爪牙之利
                                                                            ⑷悦亲戚之情话，乐琴书以消忧
                                                                                       
⑸鼎足之形成矣
                                                                            ⑹论天下事势，致殷勤之意
                                                                                          
⑺操虽托名汉相，其实汉贼也
                                                                              ⑻幼稚盈室，瓶无储粟
                                                                                       
⑼既窈窕以寻壑
                                                                                       
⑽君子博学而日参省乎己