下列程序的功能是,通过调用过程swap,调换数组中数值的存放位置,即第一个元素与最后一个元素互换,第二个元素与倒数第二个元素互换,......,程序不完整,请填空。 Option Base 1 Dim n As Integer Private Sub Command1_Click() Dim a( ) As Integer n = InputBox(" 输入一维数组容量:", "输入") 【15】_________ For i = 1 To n a(i) = i * 2 + 4 Print a(i); Next Print Call 【17】_________ For i = 1 To n Print a(i); Next End Sub Private Sub swap( 【17】_________) 【18】_________ For i = 1 To n \ 2 t = b(i) b(i) = b(k) b(k) = t 【19】_________ Next End Sub