“I sometimes get up at three or four in the morning and I surf the net．”
   “I often check my e-mail forty times a day．”
   “1 often spend more than three hours during one time on the net．"
   “I spend more time in chat rooms(聊天室)than with my‘real—life’friends．”
   Do you know who like these? They are part of a new addiction(瘾)called Internet addiction. Internet addicts spend at least thirty to forty hours online every week．The use of the Internet can be an addiction like drug(毒品)use．People lose control(控制)of the time they spend on the Internet．
   For example, one college student was missing for several days．His friends were worried．and they called the po1ice．The police found the student in the computer lab：he was surfing the net for several days straight．
   Studies show that about 6％to 10％of Internet users become addicted．And people worry about the teens because the Internet is changing the playing field for some of them．They spend more time in cyber—space than in the real world of friends and family．
   Is“surfing the net”a hobby or an addiction for you? You may have a problem if you have these symptoms(症状)
●You do not go to important family activities or you do not do school work because you like to spend hours on the Internet．
●You can’t wait for your next online time．
●You plan to spend a short time online，but then you spend several hours．
●You go out with your friends less and less．

我国肉牛生产优势区域的分布格局经历了从牧区到农区的变化过程，、逐步形成了东北、西北、西南和华北平原四大肉牛生产优势区。图2示意我国l980～2011年肉牛产业发展重心的变化。肉牛产业发展重心移动过程中（     ）

①集约化程度加大    ②良种率变化不大      ③圈养比重上升

④在肉类消费结构中，牛肉超过猪肉        ⑤牛肉商品率提高

读图，完成小题。