what does the passage mainly talk about?意思why are teenagers at risk of injuries?how can teenagers keep them safe during exercise?

What is this passag mainly about? what does the sign What does the man do? what does the man mean what does the man want what does the woman want? What does the teacher say? What does the boy ----- doing? What does the boy do “What does the writer do? what does the teacher like What does the fox say? what does the sign mean. What. does. the. shop. sell? What does the store sell? what does the speaket have What does the woman imply? What does the picture mean?