8．Have you ever heard that we humans use only ten percent of our brains？This opinion holds a certain appeal because if it were true，then we could instantly become ten times more intelligent just by firing up that sleepy majority of the brain!
The idea that we use only a small part of the brain dates back to animal experiments in the 19th century．When scientists stimulated （刺激） a specific part of the brain，the animal moved its leg or tail．If a tiny part of the brain could do something so great，what was the use of the rest of the brain？Some scientists assumed that large parts of the brain were simply useless．
Then，in the early 20th century，scientists observed that stimulating certain parts of the brain had no physical effects．They named these seemingly useless parts of the brain the"silent cortex．"Today we know that in humans，much of the"silent cortex"is actually devoted to complex activities like language，learning，and imagining．
Brain scans have shown that different parts of the brain become much more active as we shift （切換） our attention and focus，but even as we sleep，many areas of the brain are extremely active．Would you be smarter if your entire brain constantly worked to maximum capacity （能力）？Interestingly enough，the opposite is probably true．The less brain activity you need to perform a given task，the more the brain as a whole is able to do．
28．Why does the opinion mentioned in paragraph l seem appealing？A
A．People wish to become much smarter．
B．People believe it is scientific．
C．People know nothing about the brain．
D．People want to make little use of their brain．
29．What did scientists discover in their experiment in the 20th centuryC？
A．The majority of the brain is sleeping．
B．Animals'legs and tails have some connection with their brain．
C．Stimulation on some parts of the brain causes no physical reaction．
D．Certain parts of the brain are devoted to language and learning activities．
30．"Silent cortex"has proved to beB．
A．sensitive to stimulation
B．useful in complex activities
C．responsible for physical reaction
D．more active than the other parts of the brain
31．If you need less brain activity to perform a task，D．
A．you will feel sleepy
B．you must shift your focus
C．you can use your brain to the fullest
D．you will be more productive．
分析 本文為科教類閱讀，屬于科普說明文，本文主要介紹了科學(xué)研究發(fā)現(xiàn)人腦中有百分之九十沒有被使用，如果我們把這部分的作用開發(fā)出來，我們會更加聰明．同時還介紹了與此研究相關(guān)的一些其他研究成果．
解答 28．答案：A．細節(jié)理解題．根據(jù)文章第一段第二句"This opinion holds a certain appeal because if it were true，then we could instantly become ten times more intelligent just by firing up that sleepy majority of the brain!"可知，如果我們只使用了大腦的百分之十，還有百分之九十的大腦沒有被使用．若都被使用了，我們會更聰明．故選A．
29．答案：C．細節(jié)理解題．根據(jù)文章第三段第一句"Then，in the early 20th century，scientists observed that stimulating certain parts of the brain had no physical effects．"可知，20世紀的研究發(fā)現(xiàn)，刺激大腦的部分區(qū)域并不會帶來身體反應(yīng)．故選C．
30．答案：B．細節(jié)理解題．根據(jù)第三段最后一句"Today we know that in humans，much of the"silent cortex"is actually devoted to complex activities like language，learning，and imagining．"可知，這些不應(yīng)區(qū)是非常有用的．故選B．
31．答案：D．推理判斷題．根據(jù)文章最后一句"The less brain activity you need to perform a given task，the more the brain as a whole is able to do．"可知，我們做一項活動所需要的大腦活動量越少，整個大腦能夠做的事情也就越多．故選D．
點評 本文是一篇科教類閱讀，屬于說明文，題目涉及標題確定題，細節(jié)理解題，詞義猜測題．學(xué)生在做題時應(yīng)仔細閱讀原文內(nèi)容，把握文章大意，聯(lián)系文章上下文內(nèi)容及所給選項含義，從而得出正確答案，切忌胡亂猜測，一定要做到有理有據(jù)．
