China won 100 medals in the Beijing Olympic Games, which are almost ______ those of the Sydney Olympic Games.

The Sanlu Milk Powder event is a clear indication that food safety is a big problem; nobody can ___ all foods are secure to us, but we are sure that the situation is turning for the better．

— Could you give _______ an introduction to the new machine?— Of course. I will tell you how to use it. 

Young kids! You'd better apologize to us，or we________the right to accuse you of cheating.

 It is high time that we started to consider what ________  we should take to reduce heavy smog caused by traffic fumes and other pollutions.