Sometimes I get several questions but here I can only one question in 40 minutes. If I am posting more than one question in single question, I am getting objected by users. How to solve this so I can post more questions especially very relevant to Ubuntu? Thank you.
This site has a protection against users that post rubbish. Spam. That 40 minute rule is one of the hurdles in place to prevent that. And yes I have seen what happens without that rule. It is unfortunately needed to keep the frontpage useable.
AU wants you to 1st proof you are serious and you do that by answering a few questions. You gain reputation rather quickly for answering questions with a well written response.
And when you have reputation all those hurdles disappear.
125 is the magic number for this specific hurdle. I can guarantee you 125 rep in minutes: questions where you can answer by copying parts from the man page tend to get 10 upvotes and an accept.
See https://askubuntu.com/help/privileges for a list on privileges.