填空题 执行下面的程序，单击命令按钮Command1，则数组元素A(2，1)的内容是 1，A(1，2)的内容是 2，A(3，1)的内容是 3，A(1，3)的内容是 4。
Option Explicit
Option Base 1
Private A(3, 3) As Integer
Private Sub Command1_Click()
Dim B(4)As Integer, i As Integer, k As Integer, t As Integer
For i=2 To 4
B(i)=i-1
Next i
B(1)=2
For i=1 To 2
t=A(B(1), B(4))
A(B(1), B(4))=A(B(2), B(1))
A(B(2), B(1))=A(B(3), B(2))
A(B(3), B(2))=A(B(4), B(3))
A(B(4), B(3))=t
Next i
For i=1 To 3
For k=1 To 3
Print A(i, k);
Next k
Print
Next i
End Sub
Private Sub Form_Load()
Dim i As Integer, j As Integer, k As Integer
k=1
For i=1 To 3
For i=1 To 3
A(i, j)=k
k=k+1
Next i
Next j
End Sub