Nothing is more tiresome than being stuck in a boring class．Every second takes ages to tick by．A recent survey of American kids revealed that 91 percent experience boredom．In fact，adolescence is considered a peak period for the problem．One study showed that roughly one in three teenagers was bored at school．
Peter Stromberg，professor at the University of Tulsa says，"Our brains adapt really quickly to certain levels of stimulation（刺激）．We get used to the media providing levels of highly emotional stimulation，and when we're not getting them we feel bored．As our society develops various ways of keeping us entertained，we may discover that rather than getting rid of boredom，we're multiplying it．"Luckily，new research is implying a way that we can battle the trend．
Professor John D．Eastwood of the University of York developed a new theory of boredom，which links it to the brain's attention system-the part of the brain that we use to focus．Anything the attention system in your brain locks onto will be automatically sucked up into your conscious awareness-it might be a bird outside the window，the pleasant smell of lunch，or even someone sleeping in the back of the class．
The problem is that your attention system doesn't like being told what to do．It wants to focus on stuff that you find fun and interesting．For the parts of school that you enjoy，this isn't a problem．But for those classes that don't interest you，or present too much or too little challenge，the story is very different．In those situations，you're going to have to spend a lot of effort constantly redirecting your attention system to focus on things it would rather ignore．And the effort is going to wear you out．Eastwood describes it as"wanting，but being unable，to be involved in a satisfying activity．"It's like a block in the system．And it's the awareness of that block combined with a sense that the environment is to blame that leads to feelings of boredom．
When we're bored we blame the world around us，but Eastwood's theory challenges this assumption：Boredom doesn't exist out there； it exists inside your brain．What that means is-hard as it may be to hear-boring lessons aren't only the fault of your teacher or the subject，they're your fault too．

67．According to Peter Stromberg，___．
A．teenagers are victims of boredom
B．our brains demand much stimulation
C．we've grown dependent on media for fun 
D．the way we have fun makes us become bored
68．According to Paragraph 4，the attention system___．
A．doesn't like challenges
B．enjoys interesting things
C．does what you want it to do
D．can make our efforts fruitless
69．What might the author suggest about a boring class？___
A．Focusing more attention on it．
B．Changing the way we look at it．
C．Employing various teaching methods．
D．Challenging the disturbing environment．
70．What might be the best title for the passage？___
A．Escape Your Boredom
B．Battle Your Attention
C．Fun or Boredom？
D．Who Is to Blame？