title: PHP Check Sentence Contains Anything Other Than Letters
body: <p>I am trying to write a script for splitting sentences. The code works but I want to skip sentences contains anything other than letters. Such as;</p>
  
  <p>00:00:05,613 --> 00:00:16,505 
  //I want to skip this</p>
  
  <p>2</p>
  
  <p>//and this</p>
  
  <p>2.</p>
  
  <p>//and this</p>
  
  <p>The OMB guidance described in § 1.100(a) is published in subtitle A. Publication of the OMB guidance in the CFR does not change its nature—it is guidance and not regulation.</p>
  
  <p>// I do not want to skip this</p>