序数词缩写一遍是数字+其序数词最后2个字母。第一、二、三要特殊记first second 和third所以第一缩写1st,第二缩写2nd，第三缩写3rd

1至28的序数词缩写依次是：1st 2nd 3rd 4th 5th 6th 7th 8th 9th 10th 11th 12th 13th 14th 15th 16 th 17th 18th 19th 20th 21st 22nd 23rd 24th 25th 26th 27th 28th

28序数词的缩写是28th