[填空题] 下列程序计算Sn的值。Sn=a+aa+aaa+…+aaa…a,其中最后一项为n个。 例如:a=5,n=4时,则Sn=5+55+555+5555。请在空白处填入适当的内容,将程序补充完整。 Private Sub Comnmnd1_Click() Dim a As Integer,n As Integer,Cout As Integer Dim Sn As Long,Tn As LongCout=1Sn=0Tn=0a=InputBox(“请输入a的值:”)n=InputBox(“请输入n