[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&quo

A．rehcaet
B．tahreee
C．themee
D．eerthea

参考答案： A解析：[分析]：可以看出，Sub1(ByValx1AsString，y1AsString)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。

● 参考解析