How to get High PR Back Links

One of the best way to get High PR back links is give answers to related questions using below mentioned Question and Answer websites. May user those who are facing trouble ask questions on online Question and Answer websites and you can make back links by providing best and suitable answers to the questions asked on these websites.

http://www.answerbag.com
http://help.com
http://www.mahalo.com
http://www.antya.com
http://www.boakyewaaglover.com
http://answers.yahoo.com
http://www.boakyewaaglover.com