Question

could you pl explain how to make use of so long as,as long as, provided,on condition imagine, suppose , what if , i wonder .

Answer 1

Most of the time, "as long as" and "so long as" are pretty much interchangeable:
http://www.englishforums.com/English/SoLongAsVsAsLongAs/bwxjz/post.htm
and
http://grammar.ccc.commnet.edu/grammar/grammarlogs2/grammarlogs372.htm
fourth question here

So are "provided that" and "on condition" -- they all set up conditions upon which the main clause's statement would be true.

Two others in your list are verbs, and they are handled differently:
~ Imagine that you are a father with three teenagers living at home.
~ Suppose that you are a father with three teenagers living at home.

But these are different still:
~ What if you were a father with three teenagers living at home?
~ I wonder what life is like for a father with three teenagers living at home.

I hope this makes sense!