• 实例要求：
• 每0.2秒出现一个算数表达式；
• 下三角排列，呈现梯形状；
• 实例分析：
• 导入time包;
• 使用双层while循环嵌套即可；
• 示例代码：

import timei = 1
while i <= 9:j = 1while j <= i:print("%-2d× %-2d = %-2d" % (j, i, i * j), end=' ')time.sleep(0.2)j += 1print()i += 1

• 运行结果：

E:\pythonProject\venv\Scripts\python.exe E:/pythonProject/k2.py 
1 × 1  = 1  
1 × 2  = 2  2 × 2  = 4  
1 × 3  = 3  2 × 3  = 6  3 × 3  = 9  
1 × 4  = 4  2 × 4  = 8  3 × 4  = 12 4 × 4  = 16 
1 × 5  = 5  2 × 5  = 10 3 × 5  = 15 4 × 5  = 20 5 × 5  = 25 
1 × 6  = 6  2 × 6  = 12 3 × 6  = 18 4 × 6  = 24 5 × 6  = 30 6 × 6  = 36 
1 × 7  = 7  2 × 7  = 14 3 × 7  = 21 4 × 7  = 28 5 × 7  = 35 6 × 7  = 42 7 × 7  = 49 
1 × 8  = 8  2 × 8  = 16 3 × 8  = 24 4 × 8  = 32 5 × 8  = 40 6 × 8  = 48 7 × 8  = 56 8 × 8  = 64 
1 × 9  = 9  2 × 9  = 18 3 × 9  = 27 4 × 9  = 36 5 × 9  = 45 6 × 9  = 54 7 × 9  = 63 8 × 9  = 72 9 × 9  = 81 进程已结束,退出代码0