1. (2017高一上·台州期末) 现有如下Visual Basic程序：

Private Sub Command1_Click()

    Dim i As Integer, c As String, s As String, t As String

    s = Text1.text

    t = ""

    For i = 1 To Len(s)

        c = Mid(s, i, 1)

        If c >= "0" And c <= "9"  Then t = t + c

    Next i

    Text2.text = t

End Sub

运行该程序，在文本框Text1中输入“2016_Student”（不包含引号），单击命令按钮Command1后，文本框Text2中显示的内容是。