```
public abstract class A {
    abstract void polo();
}

class B extends A {
}

```

My doubt is if I give `abstract` keyword in class `B` means it wont shows anything

```
abstract class B extends A {
}

```

Why its not showing the message here to implement methods in class A - this is my doubt.

If I didn't give abstract keyword means class `B` indicates like this 

> 
> The type B must implement the inherited abstract method A.polo()
> 
> 
> 

What's wrong with that one. Can abstract class extend another abstract class or not.