序数词first second third fourth fifth sixth seventh eighth ninth tenth eleventh twevlfth thirteenth fourteenth fifteenth sixteenth seventeenth eighteenth nineteenth twentieth twenty- first twenty-second twenty-third twenty-fourth twenty-fifth twenty-sixth twenty-seventh twenty-eighth twenty-ninth tirtieth基数词：1 one 2 two 3 three 4 four 5 five 6 six 7 seven 8 eight 9 nine 10 ten 11 eleven 12 twelve 13 thirteen 14 fourteen 15 fifteen 16 sixteen 17 seventeen 18 eighteen 19 nineteen 20 twenty 21 twenty-one 22 twenty-two 23 twenty-three 24 twenty-four 25 twenty-five 26 twenty-six 27 twenty-seven 28 twenty-eight 29 twenty-nine 30 thirty