用于实现自动登陆2个邮箱，登陆进去一个退出，再登陆进去一个再退出。现在有个问题，第2个邮箱登陆进去之后不能自动退出，网页不能自动关闭。请大家看看，怎么改？谢谢

Dim a
Set a=WScript.CreateObject("WScript.shell")
a.run "http://www.126.com/"
WScript.Sleep 3000
a.SendKeys "用户名1"
a.SendKeys "{TAB}"
a.SendKeys "密码1"
a.SendKeys "{TAB}"
a.SendKeys "{ENTER}"
WScript.Sleep 15000
Set a=WScript.CreateObject("WScript.shell")
a.run "http://www.126.com/"
WScript.Sleep 3000
a.SendKeys "用户名2"
a.SendKeys "{TAB}"
a.SendKeys "密码2"
a.SendKeys "{TAB}"
a.SendKeys "{ENTER}"
WScript.Sleep 15000

Dim b,c
Set b=WScript.CreateObject("WScript.shell")
c=1

Do
if c=6 then exit do
wscript.sleep 3000
If b.AppActivate("网易126免费邮") = True Then
b.SendKeys "%{F4}{F4}{F4}"
If b.AppActivate("网易电子邮箱") = True Then
b.SendKeys "%{F4}{F4}{F4}"
exit do
end if

c=c+1
Else
exit do
End If

Loop

set b=nothing