—Do you know the boy is sitting next tu Peter?--Yes, he is Peter’s friend.They are celebrating his birthday.
It is clever ________ you ________ me work out the maths problem.
There is ________ in the classroom, so we can see ________.
We should prevent the children ________ the bad programmes.
The Olympics ________ every four years. And the 29th Olympics ________ in Beijing in 2008.
I think ________ necessary ________ to take more exercise.