there is the question. i wanna copy some information from a gov website. i did write to them is that ok to copy their information and put it on my website, they told me it is ok, because it is gov website, there is no copy right about it. but i wanna to use those information to sell ads, is that still ok?
You can use the vast majority of the US government information. Some information is not theirs (especially images) so you just have to read the terms of the particular site. Also realize that any content you copy is going to be considered duplicate content and you might have problems getting it indexed, and even if it is, you'll never rank over a .gov site for it. It would be a lot better to have the content rewritten if you are trying to rank for any of it.