单项选择题

程序段如下,程序运行后消息框显示的结果是______。 Dim a, s As String, i As Integer a = "晴空万里" s = "" For i = 1 To 4 Step 2 s &= Mid(a, 4 - i, 2) Next MsgBox(s)

A、晴空万里
B、万里晴空
C、晴空
D、万里