Did i allow to sell some of my site empty space to others site and put adsense together? I saw a lot site display other site ads. together with adsense ad. Did this against TOS?
If you mean that you have adsense on your site and have some free space that others can buy. Yes, you can do that.
It is not against the TOS? Did it not consider contentual ads? Adsense will only not allow ads with competitor?
You can put any ads on the adsense pages as long as the other ads are not contextual. Contextual ads are ads that automaticly changes to your websites theme. You can sell all the banner space you want.