急求:VB中如何设计程序在组合框中增加或者减少的可选项

Option Explicit
Dim A As String

Private Sub Command1_Click()
A = InputBox("", "", "") '输入
If A = "" Or A = "0" Then
MsgBox "没有项目被添加"
Else
With Combo1
.AddItem A '增加
.ListIndex = .ListCount - 1
.SetFocus
.SelStart = 0
.SelLength = Len(.Text) '跳转到添加的项目，并选择
End With
End If
End Sub

Private Sub Command2_Click()
With Combo1
If .ListCount And .ListIndex <> -1 Then .RemoveItem .ListIndex '删除当前选择项
End With
End Sub

Option Explicit

Private Sub Command1_Click()
Combo1.AddItem "A" & Rnd() * 10 '增加
End Sub

Private Sub Command2_Click()
If Combo1.ListCount Then Combo1.RemoveItem Combo1.ListIndex '删除当前选择项
End Sub