在窗体上画一个命令按钮(名称为Command1)，并编写如下代码：
Function Fun1(ByVal a As Integer, b As Integer) As Integer
Dim t As Integer
t=a-b:b=t+a:Fun1=t+b
End Function
Private Sub Command1_Click()
Dim x As Integer
x=10
Print Fun1(Fun1(x, (Funl(x,x-1))),x-1)
End Sub
程序运行后，单击命令按钮，输出结果是
A．10
B．0
C．11
D．21
