1.数字
基数词one   two   three  four   ★five   six    seven   eight    nine    ten
序数词                fourth        sixth                               
基数词  eleven      ★twelve       thirteen     fourteen      fifteen
序数词                                                      
基数词  sixteen     seventeen    eighteen     nineteen      ★twenty
序数词                                                       
基数词 twenty-one    twenty-two   twenty-three    twenty-four    twenty-five
序数词                                                              
基数词  thirty       thirty-one       forty          fifty          sixty       
序数词                                                            
◇基数词与序数词的区别：基数词是“第…”的意思,前面都有单词the