基数词：表数量序数词：表顺序
基变序，有规律。

字母结尾t,d,d.
其他后边th. th中有例外：八减t,就减e,f代ve,ty变tie
基数词和序数词的练习题
一、写出下列词的序数词
1. one
2.two
3. six
4.five
5.nine
6.twelve
7.eight 8.twenty-one
二、写出下列单词的基数词
1.third
2.fourth
3.tenth
4.twentieth
5.nineteenth
6.thirty-first _
三、根据句子意思填空。

1. Children’s Day（儿童节） is on the of June（六月）.
2. There are months（月）in a year(年).
3. Teacher’s Day(教师节) is on the of September（九月）.
4. Three plus(加) six is .
四、选择填空。

( )1. My cousin’s birthday in on the of October.
A. three
B. first
C. the second
( )2. What date is it today? It’s of April.
A. twelfth
B. the 12th
C. 12th
( )3. There are days in a week.
A. the seven
B. seventh
C. the seventh
D. seven ( )4.Sunday is the day of a week.
A. one
B. first
C. second
( )5. Twenty-eight minus(减)six is .
A. the twenty- second
B. twenty-two
C. twenty- second ( )6. Four plus(加) is twelve.
A. seven
B. eight
C. nine。