下面程序段运行后，s2的值为_________。Dim i As IntegerDim s1, s2 As Strings2 = ""s1 = "程序设计VB.NET"For i = 1 To Len(s1) s2 = Mid(s1, i, 1) & s2Next
A、TEN.BV计设序程
B、程序设计VB.NET
C、VB.NET程序设计
D、程序设计