单选题 若有以下两个过程：
Sub S1(ByVal x As Integer, ByVal y As Integer)
im t As Integer
t=x
x=y
y=t
End Sub
Sub S2(x As Integer, y As Integer)
Dim t As Integer
t=x: x=y: y=t
End Sub
则下列说法中，正确的是______。