【单选题】有如下子过程: Sub proc () Dim ch As String Open "file1.txt" For Input As #1 Open "file1_bak.txt" For Output As #2 Do While Not EOF ( 1 ) ch = Input$ ( 1, #1 ) Print #2, ch; Loop Close #1, #2 End Sub 这个过程的功能...
【单选题】有如下过程: Sub proc() Dim ch As String Open "file1.txt" For Input As #1 Open "file1_bak.txt" For Output As #2 Do While Not EOF(1) ch = Input$(1, #1) Print #2, ch; Loop Close #1, #2 End Sub 这一过程的功能是 ______...