问一个菜鸟级的VB问题

Private Sub Command1_Click()
Dim 人数 As Integer, 成绩 As Single, 合计 As Single, 最高分 As Single, 及格人数 As Integer
Do
成绩 = Val(InputBox("请输入第" & 人数 + 1 & "位的成绩"))
If 成绩 >= 0 And 成绩 <= 100 Then
合计 = 合计 + 成绩
人数 = 人数 + 1
If 成绩 >= 60 Then 及格人数 = 及格人数 + 1
If 成绩 > 最高分 Then 最高分 = 成绩
End If
Loop Until 成绩 = -1
Print "人数："; 人数
Print "平均分："; 合计 / 人数
Print "最高成绩："; 最高分
Print "及格率："; 及格人数 / 人数 * 100; "%"
End Sub

Option Explicit

Private Sub Command1_Click()
Dim max As Single
Dim avg As Single
Dim i As Integer
Dim k As Integer
Dim sum As Single
Dim fen As Single
Dim a()
Do
fen = Val(InputBox("输入分数："))
If fen = -1 Then Exit Do
If fen >= 0 And fen <= 100 Then
ReDim Preserve a(i)
a(i) = fen
Print a(i);
If a(i) >= 60 Then k = k + 1
If a(i) &