C

The most popular PE class at Waukegan High School in Illinois，US，takes place in a basement field house．

It is the school’s version of CrossFit，the difficult physical exercise that has exploded in popularity over the last 16 years at thousands of gyms．It has more than one million devotees and a professional competition shown on ESPN．

Schools around the Chicago area have adopted CrossFit to interest students at a time of a rising weight problem among young people，and most say it really works compared with traditional gym classes．

“I think it’s a great way to teach kids lifelong fitness，especially those kids who aren’t interested in hockey，soccer or basketball，”said the teacher，Tracy Haraf from Illinois’Stony Creek Elementary, which devotes half of its PE days to CrossFit exercises．“They think it's tough，but I think they have a lot of fun doing it．”

Senior Alexus Wiltz，18，said the workout had improved her performance on the basketball court．“I noticed I was faster．I paid more attention on the court，my defending was better,”she said after a recent class．“It just really helped me．”

But some doctors and researchers advise caution，saying the exercises that involve lifting weights can lead to injuries，particularly when performed by few inexperienced people．

Doctor Craig Finlayson at Lurie Children’s Hospital of Chicago said he was worried that while strength training is fine for kids，heavy weights could be trouble for teenagers who might hurt themselves by trying to do too much or using poor form．

CrossFit Inc．，the company that certifies trainers and licenses gyms，disagrees that its program is more dangerous than other fitness routines．Gym teachers in Waukegan’s Greg Moisio，whose two-campus school has about 73％kids taking CrossFit each day，also say the risk of injury can be reduced with proper teaching and CrossFit’s flexibility．

28．Why have schools around the Chicago area adopted CrossFit?

A．To improve students’performance in competitive sports．

B．To introduce something more challenging to the students．

C．To make traditional gym classes more attractive．

D．To help solve the students’weight problem．

29．How do the students react to the strength training?

A．73％agree it has a bad influence． B．They show little interest in it．

C．The majority believe it’s effective． D．Most of them think it’s of no use．

30．What does the underlined word“workout”in Paragraph 5 refer to?

A．The physical exercise． B．The basketball court．

C．Wiltz’s performance． D．A lot of fun．

31．What can we learn from the last paragraph?

A．CrossFit is more dangerous than other fitness routines．

B．The number of the injured in CrossFit classes is rising．

C．Kids may protect themselves if they’re trained properly．