单击窗体时，下列程序的执行结果是()。 Private Sub Invert(By Val xstr As String，ystr As String) Dim tempstr AS String Dim I AS Integer I=Len(xstr) Do While I＞=1 tempstr=tempstr + Mid(xstr，I，1) I=I - 1 Loop yStr=tempStr End Sub Private Sub Form_Click( ) Dim s1 As String，s2 As String S1="abcdef" Invert S1，S2 Print S2 End Sub
A．blooean isAlive( )
B．Thread currentThread( )
C．String getName( )
D．smtic boolean interrupted( )
