一、口算。
$2 + 9 =$
$15 - 9 =$
$11 - 3 + 9 =$
$12 - 7 =$
$7 + 6 =$
$13 - 7 + 8 =$
$6 + 8 =$
$12 - 3 =$
$8 + 7 - 5 =$
$16 - 9 =$
$4 + 8 =$
$14 - 7 + 6 =$
$14 - 8 =$
$11 - 1 =$
$5 + 9 - 8 =$
$13 - 6 =$
$9 + 3 =$
$17 - 8 - 5 =$
$5 + 12 =$
$16 - 8 =$
$12 - 8 + 5 =$
$11 - 8 =$
$5 + 9 =$
$3 + 9 - 5 =$
$7 + 7 =$
$12 - 6 =$
$14 - 5 + 7 =$
$15 - 8 =$
$9 + 7 =$
$5 + 7 - 4 =$

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

二、在$□$里填合适的数。
$9 + □ = 16$
$□ - 9 = 4$
$6 + □ = 14$
$□ - 5 = 8$
$11 - □ = 7$
$□ + 7 = 13$
$14 - □ = 7$
$□ - 8 = 8$
$8 + □ = 12$

二、7 13 8
13 4 6
7 16 4