A． The number of school injuries has doubled in ten year
B． About 20% of American children and teenagers are overweigh
C． Only 2% of the injuries treated in hospitals are seriou
D． Injuries increased 1．5 times as many as that during the past decad
A． are more competitive
B． are less risky
C． involve more activities
D． provide less choices
A． Less school nurse
B． Less field activitie
C． Larger class size
D． The introduction of new sport
A． On
B． Thre
C． Fou
D． Seve