请求最简单的判断方式,如下,该如何处理

请求最简单的判断方式,如下
if   expression= "A "   and   "B "   then
      msgbox   "running   1 "
endif
if   expression= "C "   and   "D "   then
    msgbox   "running   2 "
endif
if   expression= "K "   and "S "   then
      msgbox   "running   3 "
endif
if   expression= "Y "   and "T "   then
      msgbox   "running   4 "
endif
对于上面如果只出现上面表达示的所判断条件则为真时则运行相应的msg
但是否又怎么处理呢?如果改变else的话,就会出现层层嵌套的方式去判断,当然如果就只有这么多的话,写一次就可以了,但是以后有新的条件判断的话,这时又要去嵌套,那么有没有更简单的办法来处理这个问题呢?
thanks


[解决办法]

Select Case expression
Case "A ", "B "
MsgBox "running 1 "
Case "C ", "D "
MsgBox "running 2 "
Case "K ", "S "
MsgBox "running 3 "
Case "Y ", "T "
MsgBox "running 4 "

Case Else
MsgBox "no running "
End Select