主题：EXCEL中的多个sheet如何遍历?

如何在下面代码中加入对EXCEL中的多个sheet的遍历?

        Dim Book1 As New XLS.Book(file)
        Dim Sheet1 = Book1.Sheets(0)
                    
            For i As Integer = 0 To Sheet1.Rows.Count-1
               
                For j As Integer = 0 To Sheet1.Cols.Count -1
                   
                    If Sheet1(i, j).Text > ""  AndAlso dic.ContainsKey(Sheet1(i, j).Text) Then
                            Sheet1(i, j).value = Sheet1(i, j).Text & vbcrlf & dic(Sheet1(i, j).Text)
                            
                Next
            Next