Getting words from a line of text

Hi,

Can anyone suggest a way to get 2 words together from each other word.

Example;

UN nuclear watchdog refers Syria to Security Council

I need to export this;

UN nuclear
nuclear watchdog
watchdog refers
refers Syria
Syria to
to Security
Security Council

I was thinking using


$line = "UN nuclear watchdog refers Syria to Security Council";
list($worda, $wordb, $wordc, $wordd, $worde, $wordf, $wordg) = split(' ', $line);


<?php
$pairs = array_chunk(
  explode(' ', 'UN nuclear watchdog refers Syria to Security Council'),
  2
);

print_r($pairs);

/*
  Array
  (
    [0] => Array
    (
      [0] => UN
      [1] => nuclear
    )
    [1] => Array
    (
      [0] => watchdog
      [1] => refers
    )
    [2] => Array
    (
      [0] => Syria
      [1] => to
    )
    [3] => Array
    (
      [0] => Security
      [1] => Council
    )
  )
*/