序數詞： first， second， third ，fourth, fifth, sixth, seventh, eighth, ninth, tenth，eleventh, twelfth, thirteenth, fourteenth, fifteenth, sixteenth, seventeenth, eighteenth, nineteenth, twentieth.

基數詞：One two three four five，six，seven，eight，nine，ten，eleven，twelve，thirteen，fourteen，fifteen，sixteen，seventeen，eighteen，nineteen，twenty

第1～第20依次是

first second third fourth fifth sixth seventh eighth ninth tenth eleventh twelfth thirteenth fourteenth fifteenth sixteenth seventeenth eighteenth nineteenth twentieth

基數詞，one, two three four five six seven eight nine ten eleven twelve thirteen fourteen fifteen sixteen seventeen eighteen nineteen twenty 序數詞，first second third fourth fifth sixth seventh eighth ninth tenth eleventh twelfth thirteenth fourteenth fifteenth sixteenth seventeenth eighteenth nineteenth twentieth

在英語中數詞分為兩種，第1種是基數詞，表示人或物的數量，如one,two,three,four等，第2種是序數詞，表示人或物的順序。1~20的序數詞是: first, second ,third,fourth ,fifth,sixth,seventh,eighth,ninth,tenth,eleventh,twelfth,thirteenth,fourteenth,fifteenth,sixteenth,seventeenth,eighteenth,nineteenth,twentieth.