句子成分分析法的主要优点和缺点是什么？

下列数组声明正确的是( )。

A．n=5
Dim a(1 to n) As Integer

B．Dim a(10) As Integer
ReDim a(1 To 12)

C．Dim a() As Single
ReDim a(3,4) As Integer
ReDim a(1 to n)As Integer

D．Dim a() As Integer
n=5