新手请教一个有关Option Strict On设置下不允许后期绑定的问题

[我是小神奇]

这是我的一个练习的代码：
Module Module1



Sub Main()


Dim a_row As New ArrayList

Dim x As Integer = 1

For a As Integer = 0 To 3
Dim a_col As New List(Of Integer)

For b As Integer = 0 To 4

a_col.Add(x)
x = x + 1

Next

a_row.Add(a_col)
Next

For i As Integer = 0 To a_row.Count - 1

For j As Integer = 0 To a_row(i).count - 1


Debug.Print("{0} type:{1}", a_row(i)(j), TypeName(a_row(i)(j)))


Next
Next

End Sub

End Module
如果设置Option Strict On的情况下，编译器都会对a_row(i)，a_row(i)(j)这样的地方报错“不允许后期绑定”，这个问题除了设置Option Strict Off还有别的办法么？另外我这里a_col用的是泛型的List，已经指定了元素为integer类型了，还存在隐式转换的问题么？