Do you have enough students to clean the laboratory? –No, I think we need____________ students.

Have all the students know that our class will visit the factory this afternoon.— Yes , Every student ________ about it.

Scientists say it may be five or six years_______it is possible to test this medicine on human patients.

Look ! There’s ______ football under the teacher’s desk. Let’s play ________ football, OK?

I am crazy about chocolate.—_____. That’s probably why I am becoming fatter and fatter.