题干
仔细观察下面各式：
| 1 |
| 2 |
| × |
| 3 |
| 1 |
| 2 |
| 1 |
| 3 |
| 1 |
| 3 |
| × |
| 4 |
| 1 |
| 3 |
| 1 |
| 4 |
| 1 |
| 4 |
| × |
| 5 |
| 1 |
| 4 |
| 1 |
| 5 |
（1）请你根据其中的规律再写一道这样的算式：____
（2）运用这个规律计算：
+
+
+…+
=____ ．
| 1 |
| 2 |
| × |
| 3 |
| 1 |
| 3 |
| × |
| 4 |
| 1 |
| 4 |
| × |
| 5 |
| 1 |
| × |
答案(点此获取答案解析）
\u3000\u3000
The boy is swimming in the s