填空题
设有如下程序
Private Sub Fom1_Click( )
Dim s As Integer，b As Integer
a=20：b=50
p1 a，b
p2 a，b
p3 a，b
Print"a="；a，"b=";b
End Sub
Sub pl(x As Integer，ByValy As Integer)
x=x+10
y=y+20
End Sub
Sub p2(ByVal x As Integer，y As Integer)
x=x+10
y=y+20
End Sub
Sub p3(ByVal x As Integer，ByValy As Integer)
x=x+10
y=y+20
End Sub
该程序运行后，单击窗体，则在窗体上显示的内容是：a={{U}} 【9】 {{/U}}和b={{U}} 【10】 {{/U}}。