单选题 在窗体上画一个名称为Command1的命令按钮，然后编写如下程序代码： Private Sub Command1_Click() Dim a As Integer, b As Integer a = 5: b = 10 Call mysub(a, b) Print a; b End Sub Private Sub mysub(ByRef x As Integer, y As Integer) x = x + 5 y = y * 2 End Sub 以下叙述中正确的是