题目

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（  ） A . 39 B . 30 C . -9 D . 12 答案：B

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