如何使用excel列中的字段填充comboBox？C#

using Excel = Microsoft.Office.Interop.Excel;

Excel.Application excelApp = new Excel.Application();
Excel.Workbook workbook = excelApp.Workbooks.Open("路径/文件名.xlsx");

Excel.Worksheet worksheet = workbook.Worksheets["工作表名称"];

Excel.Range range = worksheet.UsedRange.Columns["列字母"];

foreach (Excel.Range cell in range.Cells)
{
    comboBox.Items.Add(cell.Value.ToString());
}

workbook.Close();
excelApp.Quit();

using Excel = Microsoft.Office.Interop.Excel;

// ...

private void FillComboBoxFromExcelColumn(string filePath, string sheetName, string columnName, ComboBox comboBox)
{
    Excel.Application excelApp = new Excel.Application();
    Excel.Workbook workbook = excelApp.Workbooks.Open(filePath);
    Excel.Worksheet worksheet = workbook.Worksheets[sheetName];
    Excel.Range range = worksheet.UsedRange.Columns[columnName];

    foreach (Excel.Range cell in range.Cells)
    {
        comboBox.Items.Add(cell.Value.ToString());
    }

    workbook.Close();
    excelApp.Quit();
}

string filePath = "路径/文件名.xlsx";
string sheetName = "工作表名称";
string columnName = "列字母";
FillComboBoxFromExcelColumn(filePath, sheetName, columnName, comboBox1);