21．According to the comments of the Physical Education teacher，Wally______．

A．is too talkative in the class

B．1ikes to work with his classmates

C．doesn't exercise his body at the right time

D．becomes weak because he doesn't exercise at all

22．Which of Wally's subjects will attract the headmaster's attention in future?

A．Biology and Maths． B．History and French．

C．English and Chemistry． D．Physics and Physical Education．

23．Which of the following statements is TRUE according to the report?

A．Wally didn't bother his teacher to revise French．

B．Wally's potential has been fully reflected in his exam work．

C．Wally's grade in maths makes him a born scientist．

D．Wally needs to improve his attitude on certain subjects．

　　Last year，three experienced storm chasers were killed in a tornado in the US，but despite this the number of people going in search of tornadoes is growing．What drives them to take risks and look for danger? The man at the wheel glanced in the back-view mirror and then slowly turned around．"Don't put this in your program．"he said．His wife in the passenger seat laughed．He lowered the window and killed the engine．The wind rushed in from surrounding wheat fields．

　　Then，from behind，the sound of footsteps approached on the dirt road．It was a moment of peace after hours of speedy racing through the American grassland．There had been excited shouts about where a tornado might form and how we would be there if it did．We were crazy on the trail a moment ago．But now，everyone was very coo1．A Kansas state trooper(骑警) introduced himself through the window．There was pretended surprise when he said how fast we had been going．Really? Wow，sorry．

　　Val Cator handed over his driver's license．His wife，Amy，took the registration out of the glove box．Val explained they were storm chasers with Channel 9 News out of Oklahoma City-though it was hardly necessary．Their huge black truck has lightning bolts(闪电)and Storm Tracker 9 painted on the sides．

　　Val pointed to the radar on the laptop open next to him and said those red and green dots suggested a tornado could form this afternoon．The state trooper was untouched．"I've got that in my car too．"he said．People here keep a close eye on the weather．It's part of living in the tornado alley．Every year some town or other is blown off the map by tornadoes that can reach 300 miles an hour．

Val and Amy are just two of hundreds of possibly thousands of trackers who speed around with computers and cameras hoping to catch one of these beautiful，deadly storms．I'd joined them to learn why the number of trackers keeps growing．Why are people taking real risks-beyond the steady diet of rest-stop junk