Most experts agree that human activities such as the clearing of large areas of forests, and farming on a large scale _________ the problem of global warming.

. The school has recently decided that students aren’t permitted to use mobile phones at school, but I find it difficult to _______ this decision..

It’s obvious that the Beijing Olympic Games _______ a great success．

He lost his job three months ago;       , he was seriously injured in an accident last week.

 —May I have a talk with one of your reporters？ —Sorry, but all of them are out to ______the main events of the day.