title: Can "override abstract methods" be substituted with "implement abstract methods" in Java inheritance?
body: <p>In Java inheritance, can the expression "overriding an abstract method" be used interchangeably with the expression "implementing an abstract method"? </p>
  
  <p>I came across the following question in the book "OCA Java SE 8 Programmer I Study Guide" in Chapter 5, page 296, question #15:</p>
  
  <p>Q: Which of the following is true about a concrete subclass? (Choose all that apply)</p>
  
  <ul>
  <li>A. A concrete subclass can be declared as abstract.</li>
  <li>B. A concrete subclass must implement all inherited abstract methods.</li>
  <li>C. A concrete subclass must implement all methods defined in an inherited interface.</li>
  <li>D. A concrete subclass cannot be marked as final.</li>
  <li>E. Abstract methods cannot be overridden by a concrete subclass.</li>
  </ul>
  
  <p>My answer was B &amp; E. But the book says, the correct answer is only B. 
  My question is specifically about the option E. The book says, option E is incorrect because abstract methods must be overridden by a concrete subclass. My initial thought was abstract methods must be implemented before being overridden by a subclass. So why is option be incorrect?</p>