He tripped on the stairs, and could not __________ falling.
Education in many countries is compulsory________the age of 16.
Michael looked deeply hurt and surprised when_____________________ .
_______ has been a topic of continual geological research.
Regular exercise and good diet will bring______fitness and health.
The phrase "keeps sellers on their toes" in the passage mostly means "______".
Stephanie: "Oh, no! I left my book at home. Can I share yours?" Scott: "______ "
According to critics of globalization, several developed countries have become rich because of
__________ John Kennedy was elected president, he was the youngest American President ever.
The pool should not be made so deep______small children can be safe there.
We all agree that she is____________________ student in our class.