可以扩展其他类的接口吗？

I found this on zend website

interface ResultSetInterface extends \Traversable, \Countable
{
    public function initialize($dataSource);
    public function getFieldCount();
}

is it possible that interface Extend Class ? and multiple Inheritance? as i know PHP doesn't support multiple Inheritance. Click Here

can anyone clear this.

From the documentation https://secure.php.net/manual/en/language.oop5.interfaces.php

Interfaces can be extended like classes using the extends operator.

They can extend only other interfaces.