Question

excel vba 这段简单的代码该怎么解释，特别是上面那部分。

Private Sub ComboBox1_Change()
Dim str$
str = ComboBox1.Text
Dim dic, arr, i As Integer
Set dic = CreateObject("scripting.dictionary")
arr = Sheet7.UsedRange
On Error Resume Next
For i = 2 To UBound(arr)
If VBA.Left(arr(i, 4), Len(str)) = str Then
dic(arr(i, 4)) = ""
End If
Next
ComboBox1.List = dic.keys
ComboBox1.DropDown
Set dic = Nothing
Dim ob
With Sheets("Feedback")
Set r1 = .Columns(4).Find(what:=str, lookat:=xlWhole)
If Not r1 Is Nothing Then
Label13 = .Cells(r1.Row, 1)
Label14 = .Cells(r1.Row, 2)
Label15 = .Cells(r1.Row, 3)
Label16 = .Cells(r1.Row, 5)
Label17 = .Cells(r1.Row, 6)
Label18 = .Cells(r1.Row, 7)
Label19 = .Cells(r1.Row, 8)
Label20 = .Cells(r1.Row, 9)
Label21 = .Cells(r1.Row, 10)

Else
Label13 = ""
Label14 = ""
Label15 = ""
Label16 = ""
Label17 = ""
Label18 = ""
Label19 = ""
Label20 = ""
Label21 = ""

End If
End With
End Sub

Answer 1

Dim str$
str = ComboBox1.Text'combobox1赋值给变量str
Dim dic, arr, i As Integer
Set dic = CreateObject("scripting.dictionary")‘声明一个字典变量
arr = Sheet7.UsedRange'把sheet7表的数据赋值给数组arr
On Error Resume Next’遇到错误执行下一步
For i = 2 To UBound(arr)'在数组中循环
If VBA.Left(arr(i, 4), Len(str)) = str Then'判断数组中第4列数据中前面算起与str字符相同的字段是否与str相同
dic(arr(i, 4)) = ""'添加到字典中
End If
Next
ComboBox1.List = dic.keys‘把字典的key值赋值给combobox1列表
ComboBox1.DropDown'键盘向下方向键
后面就是判断，不详述了，
请别再接问下面的代码意思。谢谢