窗体上有一个名称为Command1的命令按钮。要求编写程序,把文件f1.txt的内容写到文件f2.txt中,然后将f1.txt删除。命令按钮的单击事件过程如下: Private Sub Command1_Click() Open "c:\f1.txt" For Input As #1 Open "c:\f2.txt" For Output As #2 Do While Not EOF(2) Line Input #1, str1 Print #2, str1 Loop Close Kill "c:\f1.txt" End Sub 该程序运行时发生错误,应该进行的修改是