有如下VB程序段： Dim i As Integer, sum As Integer
Dim a(1 To 6) As Integer, b(1 To 6) As Integer
sum = 0
a(6) = 18: a(5) = 7: b(6) = 14: b(5) = 16
For i = 4 To 1 Step -1
a(i) = a(i + 2) - a(i + 1)
b(i) = b(i + 2) - a(i)
If b(i) Mod 3 = 0 Then sum = sum + b(i)
Next i
Text1.Text = Str(sum)
该程序段运行后，文本框Text1中显示的内容是（ ）
