1-10 first second third fourth fifth sixth
seventh eighth ninth tenth
11-20 eleventh twelfth thirteenth fourteenth sixteenth seventeenth eighteenth nineteenth twentieth
21 twenty-first
拓展:基数词变序数词口诀: 一二三要全变,其余把th加后面,th里面有例外,八加h,九去e,ve要用f替整十基数变序数,变y为ie,再加th若是变为几十几,十位不变个位变