ser y estar

• http://www.studyspanish.com/lessons/serest1.htm
• http://www.studyspanish.com/lessons/serest2.htm
• http://www.studyspanish.com/lessons/serest3.htm
• http://www.studyspanish.com/lessons/serest4.htm
• http://www.bowdoin.edu/~eyepes/newgr/ser.htm
• http://personal.colby.edu/~bknelson/SLC/ser_estar.php
• http://www.quia.com/quiz/438253.html
• http://www.spanishspanish.com/ser_estar_practice_web.html
• http://www.stolaf.edu/people/hansonr/spanish/ser-estar/
  
• https://conjuguemos.com/activity.php?id=24&source=public&language=spanish&type=fillin
• https://conjuguemos.com/activity.php?id=25&source=public&language=spanish&
• https://conjuguemos.com/activity.php?id=26&source=public&language=spanish&type=fillin
  
• https://lenguajeyotrasluces.wordpress.com/2014/12/04/ser-y-estar/