xlwings 进程总是无法关闭

xlwings 进程总是无法关闭。close quit kill 都用了还是不行。程序运行完毕，表格就被进程占用，不能再次打开，只能手动关闭进程et.exe。求高手解答，


import xlwings as wx
import xlwings

app = wx.App(visible=False, add_book=False)  # type: xlwings.main.App
app.display_alerts = False  # 关闭一些提示信息，可以加快运行速度。 默认为 True。
app.screen_updating = False
wb1 = app.books.open(r".\1.xlsx")  # type:xlwings.main.Book
wb2 = app.books.open(r".\3.xlsx")  # type:xlwings.main.Book
sht1 = wb1.sheets["月度计划单"]  # type: xlwings.main.Sheet
sht2 = wb2.sheets["月度计划单"]  # type: xlwings.main.Sheet
info1 = sht1.used_range  # type: xlwings.main.Range
for i in info1.rows:  # type: xlwings.main.Range
    if str(i[1].value).find("600") == -1:
        pass
    else:
        list = []
        for j in i.columns:  # type: xlwings.main.Range
            list.append(str(j.value))
        info2 = sht2.used_range  # type: xlwings.main.Range
        nows = info2.last_cell.row
        for k in info2.rows:
            print(k)
            # if  str(k[1].value) == str(list[1]):
            #     break
        else:
            sht2.range(nows + 1, 1).expand('right').value = list
            sht2.range(nows + 1, 2).api.NumberFormat = "0"
wb2.save(r".\3.xlsx")
wb1.close()
wb2.close()
app.kill()
app.kill()