填空题

以下程序的目的是将多维数组a(1 To m, 1 To n)中的元素转移到一个名为b(1 To n*m)的一维数组中，完成该程序。
Option Base 1
Private Sub Command1_Click(Index As Integer)
Dim a(1 To 20, 1 To 10)
Dim b()
ReDim______
For i=1 To 20
For j=1 To 10
a(i，j)=i术j
Next j
Next i
Tran a, 20 , 10 b
End Sub
Sub Tran(a(), m, n, b())
Dim i As Integer
For i=1 To m
For j=1 To n
______=a(i，j)
Next j
Next i
End Sub