1. 把加法表补充完整。

| | 11 | 9+2 | | 7+4 | | 5+6 | 4+7 | 3+8 | 2+9 |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | 12 | 9+3 | | | 6+7 | | 4+9 | | |
| | 13 | 9+4 | | | 6+7 | | 4+9 | | |
| | 14 | 9+5 | 8+6 | | | 5+9 | | | |
| | 15 | | | 7+8 | | | | | |
| | 16 | | | | | | | | |
| | 17 | | | | | | | | |
| | 18 | 9+9 | | | | | | | |

| | 11 | 9+2 | 8+3 | 7+4 | 6+5 | 5+6 | 4+7 | 3+8 | 2+9 |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | 12 | 9+3 | 8+4 | 7+5 | 6+6 | 5+7 | 4+8 | 3+9 | |
| | 13 | 9+4 | 8+5 | 7+6 | 6+7 | 5+8 | 4+9 | | |
| | 14 | 9+5 | 8+6 | 7+7 | 6+8 | 5+9 | | | |
| | 15 | 9+6 | 8+7 | 7+8 | 6+9 | | | | |
| | 16 | 9+7 | 8+8 | 7+9 | | | | | |
| | 17 | 9+8 | 8+9 | | | | | | |
| | 18 | 9+9 | | | | | | | |
额外任务完成：
得数是13的涂色算式：$\boldsymbol{9+4，8+5，7+6，6+7，5+8，4+9}$
得数是12的写在方框里：$\boldsymbol{9+3，8+4，7+5，6+6，5+7，4+8，3+9}$

根据每行的得数，写出两个一位数相加等于该得数的算式，补充到对应空格中：
1. 得数11：补充$\boldsymbol{8+3}$，$\boldsymbol{6+5}$
2. 得数12：补充$\boldsymbol{8+4}$，$\boldsymbol{7+5}$，$\boldsymbol{6+6}$，$\boldsymbol{5+7}$，$\boldsymbol{4+8}$，$\boldsymbol{3+9}$
3. 得数13：补充$\boldsymbol{8+5}$，$\boldsymbol{7+6}$，$\boldsymbol{5+8}$
4. 得数14：补充$\boldsymbol{7+7}$，$\boldsymbol{6+8}$
5. 得数15：补充$\boldsymbol{9+6}$，$\boldsymbol{8+7}$，$\boldsymbol{6+9}$
6. 得数16：补充$\boldsymbol{9+7}$，$\boldsymbol{8+8}$，$\boldsymbol{7+9}$
7. 得数17：补充$\boldsymbol{9+8}$，$\boldsymbol{8+9}$

2. 照样子，根据房顶上的得数写算式。

9+4
7+6
7+4
6+5
10+1
8+4
7+5
9+3

3. 换气球。

5+8=13
9+6=15
交换5和6：
8+6=14
9+5=14
或交换8和9：
5+9=14
8+6=14
答：交换5和6的气球，或者交换8和9的气球，得数就一样了。