How to implement question/answer functionality with following feature? I would like to create a question/answer website using Drupal7, where a user can ask a question and other users can answer that question. This one is very simple to implement in Drupal 7. But what additional feature i want is when a user asks a question he will set the expiration period also by choosing from a select list (5Days, 7Days and 15Days etc). Within this duration the STATUS of the question should be shown as "OPEN for Answer". After this period, the STATUS should be changed to "Finalizing Best Answer" automatically and now no new answer can be submitted by any user and after the best answer is selected by the asker, the STATUS should change to "CLOSED" automatically. But the asker of the question can change this STATUS at any time from "OPEN" to "CLOSED" even befor the expiry set by himself, but he can not change any other field of the question form once a question is published. How should i implement this type of functionality in my content type? Please provide your views for this type of functionality.
Thanks!!
Well, while the Answers module does not support this entirely, it does provide some helpful functionality. (FWIW, this has been an open feature request for some time. I haven't gotten around to it ... but if you end up implementing it, I would love to integrate it.).

In particular, the Answers module allows you to programmatically "lock" questions, meaning additional answers are not allowed. You can also extend the module with the Best Answer module (which, naturally enough, enables question authors to select a Best Answer). The Best Answer module already provides an administrative setting which, if set, means that questions are automatically locked after the question author selects a Best Answer.