There are about ________ students in our school.
Andy, you’d better not eat meat only. You should know milk and fruit _______ good for you.
--________ do you go to the supermarket, Amy? -- Once a week.
You should _______ smoking. It’s really bad for your health.
Now teenagers are very busy with their schoolwork and they have _____ time to do exercise.
Sam enjoyed collecting. He has collected over three _______stamps.