6.　　绘制骰子四点的图案。
7.　　编写Java程序，创建一个窗体，并实现交互。在窗体内“单击鼠标左键”，在光标处绘制一个“绿圆”；窗体内“单击鼠标右键”，在光标处绘制一个“红色方框”；窗体内“双击鼠标左键”，清空所有已画“圆”和“方”(6. Draw a pattern of four dice.
7. Write java program, create a form, and realize interaction. In the form, click the left mouse button to draw a green circle at the cursor; in the form, click the right mouse button to draw a red box at the cursor; in the form, double-click the left mouse button to clear all drawn circles and squares)