Did you know that if you can't find the right words to respond to post with, you can post PHOTOS, VIDEOS, OR GIFs.
This is how:
Click in the comment box. You should see a "+" symbol
Click on the "+" and your options pop up. For video, it only allows links to Youtube or Vimeo. For GIFs it works the same way it does on Twitter. You just search for the mood you want and it gives you options.