Private Sub Command1_Click()Open "d:\myfirst.txt" For Output As #1Print #1, "welcome", 123.4, Date, TrueClose #1End Sub我要打开D:\盘的myfirst.txt文件,想要把盘符D:\作为一个变量,用驱动器列表框怎么来实现?使得我对myfirst.txt的更新下确写入到myfirst.txt文件里去.