问题
单项选择题
编写如下事件过程： Private sub sub1 (ByVal x1 As String, y1 As String)Dim xt As StringDim i As Integeri = Len(x1)Do While i＞= 1 xt = xt + Mid(x1, i, 1) i=i-1Loopy1 = xt End Sub Private Sub Form Click()Dim s1 As String, s2 As Strings1= "teacher"sub1 s1, s2Print s2 End Sub 程序运行后，单击窗体，则窗体上显示的内容是
A．rehcaet
B．tahreee
C．themee
D．eerthea
答案
参考答案：A
解析：
[分析]： 可以看出，Sub1(ByVal x1 As String，y1 As String)的作用是将参数x1的字符逆序处理，然后赋给y1，而y1是传址引用的，可以直接返回处理结果。