To keep ______, we must do more out-of-door exercises. 

We’re expecting Jerry because he’s our _________ visitor who comes here for holiday every summer.

After a whole day’s hard work in the field, the old peasant went home, _____. 

 With the Internet widely used, a(an)___change has taken place in the way people communicate with one another.

The increase of the number of the students in our school makes the computers not ______ to each student．