主题：请教集合

Dim ary() As String = {"a","b","ab","bc","a","b"}
Dim dic As new Dictionary(Of String, Integer)
For Each s As String In ary
    If dic.ContainsKey(s) = False Then
        dic.Add(s, 1)
    Else
        dic(s) = dic(s) + 1
    End If
Next

For Each k As String In dic.Keys
    If dic(k) > 1 Then
        output.show(k)
    End If
Next