Several things can cause bullying. It can happen when there is a (25) lack of adult control in public areas of a school, so there is no one around to stop it. Schools always say they don't allow bullying to take place, but they must do positive things to (26) prevent from happening, like having teachers on duty during intervals and on transportation to and from school. Bullying is usually against students who are seen as different in some way. These differences can be connected with physical features, such as weight, height, and hair color, or with cultural differences, like the country, the race, or the religion that someone comes (27) from. One surprising cause of bullying is a lack of self-esteem in the bully himself or herself. Students who bully may not feel secure in (28) their own bodies, nationality, or culture. Bullying can hurt the mental and physical health of the person who gets bullied. It can make them feel anxious or depressed and may cause physical problems like headaches and stomach aches. It may also lead to a student missing school and, as a result, doing (29) poorly in important examinations.