You shouldn’t have the machines ______ all the while. You ought to have them ______ now and then.

_____ by the advances in technology, many farmers have set up wind farms on their land.

 __________ to train his daughter in English, he put an advertisement like this in the paper, __________an English teacher for a ten-year- old girl.

______ a truck coming directly from the opposite direction, the car driver turned ______ right to avoid a head-on collision. 

Passengers are permitted    only one piece of hand luggage onto the plane.