4. a direct link, rising levels of obesity

e.g. I believe that there is a direct link between fast food advertisements and the rising levels of obesity.

5. be used for sth., clean-up operation, pleasant environment

e.g. The government funds can be used for clean-up operation, which can help create a pleasant environment.

6. censor, buy more than they need

e.g. It is necessary to censor some advertisements which encourage consumers to buy more than they need.