Extend an extended class in php

Can we extend from extended class in php like this:

class Milk extends Sheep {
    // some stuff
}
 
class Sheep extends Animal {
    // some stuff
}
 
class Animal {
    // some stuff
}

PHP:

Can we inherit this way or this is not allowed? If I cannot do this, then what are possible options?

 

You can absolutely extend multiple classes! Quick demo:

<?php
 
class Animal {
    // some stuff
}
 
class Mammal extends Animal {
    public function birth() {
        return'Live young';
    }
}
 
class Primate extends Mammal {
    public function hasBodyHair() {
        return true;
    }
}
 
class Human extends Primate {
    private$name;
    
    publicfunction__construct($name) {
        $this->name = $name;
    }
    
    public function getName() {
        return $this->name;
    }
    
    public function useTools() {
        return true;
    }
}
 
 
$human = new Human('John Doe');
printf("Our human %s:\n", $human->getName());
printf("\t%s tools\n", $human->useTools() ? 'uses' : 'does not use');
printf("\t%s body hair\n", $human->hasBodyHair() ? 'has' : 'does not have');
printf("\tgives birth to %s", $human->birth());

PHP:

Output:

Our human John Doe:
   uses tools
   has body hair
   gives birth to Live young

Code (markup):

 

Can you please explain with a few words why and what?