________ we clean the classroom at once—No, you________. You ________clean itafter school

It was __________ computer games that costthe young man a lot of precious time that heshould __________ on his lessons．

n this way, directed by theteacher, ______work out the problem the day before.

______ nearly all behavior is learned behavioris a basic assumption ______ has been put forward by the social scientists.

Mary likes eating vegetables, such as potatoes, tomatoes and _________.