v.退订；取消订阅
If you would liketo opt out of receiving email, you may unsubscribe at any time. 如果您决定不接受此类邮件，可在任何时候退订。
End users are able to subscribe and unsubscribe to the published alerts made available to them. 终端用户能够订阅他们可获得的发布警示信息，并可取消订阅。
