In our class there are 60 students, of ____________ two thirds are boys.
Two lawyers have donated $50,000 to ________ our school's campaign "Help the Needy", whichwas started by our former headmaster three years ago.
The experiment shows that proper amounts of exercise, if regularly, can improve our health.
This coastal area a national wildlife reserve last year.
The boy disappeared in the village five years ago and he ever since.
We've had a good start, but next, more work needs ________ to achieve the final success.