D选项解释错误 optionally-bounded、unbounded不是一回事，LinkedBlockingQueue,LinkedBlockingDeque应该都是optionally-bounded即可选有界，而不是无界 源码如下     public LinkedBlockingQueue() {         this(Integer.MAX_VALUE);     }     public LinkedBlockingQueue(int capacity)      public LinkedBlockingDeque() {         this(Integer.MAX_VALUE);     }     public LinkedBlockingDeque(int capacity)  jdk8文档也是如此描述 An optionally-bounded blocking queue based on linked nodes.  https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/LinkedBlockingQueue.html An optionally-bounded blocking deque based on linked nodes. https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/LinkedBlockingDeque.html