如何在' - '之前用php [关闭]提取每个单词

How can I exrtact every word before -. What I mean is if I have

word - word word
or
word word2 - word word
or 
word word2 word3 - word word

I need every word before -

<?php
  $line="word word2 word3 - word word";
  $words=explode(" ",trim(substr($line,0,strpos($line,"-"))));
  print_r($words);
?>

Demo

One Liner

print_r(explode(" ",trim(substr($line,0,strpos($line,"-")))));