title: How to find strings that only contains two words (each words can only have A-Z or a-z characters)?
body: <p>I have a couple of strings and I only want to display the string that has two words.</p>
  
  <p>Each word can only contain A-Z or a-z</p>
  
  <p>(Each string below has a new line)</p>
  
  <pre><code>"AIR CLEANING" &lt;- true
  "AIR CLN ASM C27w CLUTCH" &lt;- false
  "AIR COMPO. LUBRICATOR" &lt;- false
  "AIR COMP" &lt;- true
  "O-RING" &lt;- false
  </code></pre>