It was playing computer games______ cost the boy plenty of time_____ he ought to have spent doing his homework.

It is difficult for children to change their eating habit later in life.________，parents should encourage healthy eating from an early age.

Look at these tracks. It _____ be a wolf.” —Don’t be so sure. I think it _____ be a fox.

Last weekend Peter had a great deal of fun with his family________kites in a park.

Billy really likes listening to different kinds of music, so the CD must belong ________.