$re = '/\s(([a-zA-Z]+\-[a-zA-Z]+|[a-zA-Z]+)\.)/';
$str = '<p>With consumers becoming more and more health-conscious by the minute, the wearable fitness tracker market is ever-expanding.</p>
<p>So, to cut through the clutter, we created a lifestyle video series and an interactive kiosk experience at Best Buy, where we were able to inform and educate consumers about Jawbone’s Up products right there at point of sale.</p>
<p>By arming consumers with the knowledge on how to improve their personal physical fitness, they’re able to make informed decisions with the push of a button. As part of the experience, visually stimulating films helped people easily understand each product’s features and benefits as well as identify which product best fit their needs.</p>
<p>The lifestyle and product demonstration films within the interactive experience were also used across social media, the Jawbone website, and as TV spots in two countries.</p>
<div class="image"><a href="http://goldenarm.com/staging/wp-content/uploads/2015/06/UpKiosk.jpg"><img class="aligncenter wp-image-1156 size-large" src="http://goldenarm.com/staging/wp-content/uploads/2015/06/UpKiosk-1024x643.jpg" alt="" width="1024" height="643"></a><img class="aligncenter wp-image-1348 size-large" src="http://goldenarm.com/staging/wp-content/uploads/2015/06/6.-youpush-1600px-1024x576ABC.jpg" alt="" width="1024" height="576"></div>
<p class="work-page__video_container"><div class="video-embed"><iframe src="https://player.vimeo.com/video/122136552" width="500" height="281" frameborder="0" allowfullscreen="allowfullscreen"></iframe></div><br>
<div class="video-embed"><iframe src="https://player.vimeo.com/video/122136232" width="500" height="281" frameborder="0" allowfullscreen="allowfullscreen"></iframe></div></p>
<div class="image"><a style="font-size: 20px;" href="http://goldenarm.com/staging/wp-content/uploads/2015/06/Screen-Shot-2015-06-23-at-2.55.39-PM.png"><img class="alignnone size-full wp-image-857" src="http://goldenarm.com/staging/wp-content/uploads/2015/06/Screen-Shot-2015-06-23-at-2.55.39-PM.png" alt="Screen Shot 2015-06-23 at 2.55.39 PM" width="639" height="638"></a></div>';
$subst = " $1";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php