我有点卡住了。这是我的代码:letspeaker=AVSpeechSynthesizer()varplayQueue=[AVSpeechUtterance]()//currentqueuevarbackedQueue=[AVSpeechUtterance]()//queuebackup...funcmoveBackward(_currentUtterance:AVSpeechUtterance){speaker.stopSpeaking(at:.immediate)letcurrentIndex=getCurrentIndexOfText(currentUtterance)//outo