在窗体上画一个命令按钮,然后编写如下程序: Sub S1(By Val x As Integer, By Val y As Integer) Dim t As Integer t=x x=y y=r End Sub Private Sub Command1_Click() Dim a As Integer, b As Integer a=10 b=30 S1 a,b Print a= ; b= ;b End Sub 程序运行后,单击命令按钮,.输出结果是______。
A.a=30 b=10
B.a=30 b=30
C.a=10 b=30
D.a=10 b=10