Observable Contract的订阅和取消订阅部分对您的问题具有明确性.它指出：
When an Observable issues an OnError or OnComplete notification to its observers,this ends the subscription. Observers do not need to issue an Unsubscribe notification to end subscriptions that are ended by the Observable in this way.
在Observable Termination部分中也提到了这一点：
When an Observable issues an OnError or OnComplete notification to its observers,this ends the subscription.
