一、口算。
$12 - 7 =$ $7 + 6 =$ $11 - 9 + 8 =$
$5 + 6 =$ $12 - 3 =$ $3 + 7 + 5 =$
$16 - 9 =$ $4 + 8 =$ $15 - 8 + 7 =$
$8 + 9 =$ $14 - 9 =$ $9 + 5 - 8 =$
$13 - 6 =$ $9 + 3 =$ $17 - 8 - 5 =$
$5 + 8 =$ $16 - 8 =$ $12 - 8 + 5 =$
$11 - 8 =$ $5 + 9 =$ $4 + 9 - 6 =$
$7 + 7 =$ $12 - 6 =$ $14 - 5 + 7 =$
$17 - 9 =$ $7 + 8 =$ $5 + 7 - 3 =$
$8 + 8 =$ $13 - 9 =$ $16 - 7 + 5 =$

一、5 13 10
11 9 15
7 12 14
17 5 6
7 12 4
13 8 9
3 14 7
14 6 16
8 15 9
16 4 14

二、找规律，填一填。

二、7 8 9