单项选择题

单击命令按钮时，下列程度段的执行结果为( )。 Pfivate Sub Command1_Click() Dima As Integer，b As Integer, c As Integer a=2:b=4:c=6 Call S1(a，b) Print "a="；a；"b="；b；"c="；c Call S2(a，b) Print "a="；a；"b="；b；"c="；c； End Sub Private Sub S1(x As Integer, y As Integer) Dim c As Integer x=2*x:y=y+2:c=x+y End Sub Sub S2(x As Integer, By Val y As Integer) Dim e As Integer x=2*x:y=y+2:e=x+y End Sub