inherited method call - I got it!

First, thank all of you for your guess & tips.

It wouldn't be so weird to find the right answer if I was thinking about the similarity of PHP and C++ syntax.

and one more pleasure, function overriding is enable and working correctly and all the functions are virtual! OO
supportof PHP is great! (except multiple inheritance) 

So I 've got the answer, look:

 class A {
// you've already known it!
 }

 class B extends A
 {
     function f1($x)
     {
         A::f1($x*4); //  ancestor class name double colon as the same in C++
         $this->x *= 2;
     }
}