How to change the comment link text "Login or register to post comment" to be shorter eg " comment" in drupal

1. I have created a Q&A type using
   Create Content in drupal.




2. I have created a new content name
   Ask and Answer.




3. Until this i don't have any issues.
   Now problem is i have enabled
   comments in content type.




4. In this case i need to change the
   "Add new comment" or similar links
   related to comments as "Answer"
   without changing the core comment
   module.




5. How can i do this?

Thanks in advance.

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