It’s a good habit to turn off the unnecessary lights, it can help save .
When I went into the classroom, to my _____, all of the students stood up together.
He used to watch TV or ______ computer games at home on weekends.
—How do you study _________ a test? —I often study _______ a group.
This is ______ book. They like it very much.
______ his shoes under the bed?