Which two statements are true?（）

• A、It is possible for more than two threads to deadlock at once.
• B、The JVM implementation guarantees that multiple threads cannot enter into a deadlocked state.
• C、Deadlocked threads release once their sleep() method's sleep duration has expired.
• D、Deadlocking can occur only when the wait(), notify(), and notifyAll() methods are used incorrectly.
• E、It is possible for a single-threaded application to deadlock if synchronized blocks are used incorrectly.
• F、If a piece of code is capable of deadlocking, you cannot eliminate the possibility of deadlocking by inserting invocations of Thread.yield().