下面的短文后列出了7个句子，请根据短文的内容对每个句子做出判断：如果该句提供的是正确信息，请选择A;如果该句提供的是错误信息，请选择B;如果该句的信息文中没有提及，请选择C。
Some Schooling on Backpacks
According to the U.S. Consumer Product Safety Commission. 5.900 kids were treated at hospital emergency rooms, clinics, and doctors’offices last year for sprians(扭伤)and strains caused by backpacks. Such injunes are so widespread that more than 70 percent of physicians as a potential clinical problem for children.
How do you avoid such problems? Choose bags that have wide, padded straps(有垫的背带)and a belt. That will help transfer some of the weight from the back and shoulders to the hips. You should also tighten both straps firmly, so the pack rests about 2 inches above your waist. Also, remember to pack your bag with the heaviest items closest to your back and to bend both knees when you pick it up.
I low much should you stuff into your pack? That depends on your size and strength, but a general rule is not to exceed 20 percent of your body weight. So if a child weights 100 pounds, the backpack and its load should not be more than 20 pounds. One hint: Make frequent trips to your locker(储物柜)to exchange books between classes.
Backpacks with wheels let you pull the weight along the ground,but they have problems too. Many are larger than the average shoulder bag, so students are tempted to carry more than they would in a conventional pack.
Roller bags often don’t fit into a locker. They can also lead to tripping and falls in crowded halls. Whatever you use. 10 or 15 minutes of stretchin医学全.在.线www.med126.comg and back strengthening is a good idea.
16.About six thousand American kids were injured by carrying backpacks last year.
A. Right
B. Wrong
C. Not mentioned
答案：B
17.70 percent of UK physicians have treated children with sprains and strains.
A. Right
B. Wrong
C. Not mentioned
答案：B
18.Backpacks with wide, padded straps and a belt can help to avoid problems of sprains and strains.
A. Right
B. Wrong
C. Not mentioned
答案：A
19.A 100-pound child should carry a backpack of more than 20 pounds.
A. Right
B. Wrong
C. Not mentioned
答案：B
20.Children should put all the books in their locker.
A. Right医学全.在.线www.med126.com
B. Wrong
C. Not mentioned
答案：B
21.Roller bags tend to be heavier than ordinary backpacks.
A. Right
B. Wrong
C. Not mentioned
答案：C
22.A 10-15 minutes’exercise will help you bear a heavier backpack.
A. Right
B. Wrong
C. Not mentioned
答案：A
