19．We all know that eating junk food can make us fat．However，a new study suggests that it can do more than that-it can also make us lazy，reported CBS News．
In the study，researchers at the University of California，Los Angeles，US divided 32female rats into two groups．The first group was fed a diet of healthy food such as corn and fish，while the second was given a diet of highly processed （加工的） food rich in sugar，namely"junk food"．
Within three months，the rats in the second group were already much fatter than those on the healthy diet．And when researchers trained the rats to do simple tasks，they found even more differences between the two groups rather than weight．
During the task-pushing a lever （杠桿） to receive a reward of sugar water-the rats on the junk food diet were found to be less willing to move，and they took longer breaks between each push than the lean rats did．
"It is as if the rat is thinking‘This is too much work'，"Aaron Blaisdell，leader of the study，told the Los Angeles Times．
But what about the possibility that the fat rats were less passionate about getting sugar water because they were already eating lots of sugar in their daily diet？That's why researchers repeated the tests by rewarding fat rats with plain water when they were extremely thirsty．However，the results came out just the same．
According to researchers，these differences suggest that junk food changed the chemistry in the rats'brains．
The experiment didn't end there．After six months，the rats'diets were switched，and the overweight rats were given a healthy diet for nine days．However，this change didn't help reduce their weight or improve their ability to perform tasks，which means the effects of their junk food diet persisted （持續(xù)存在）．"There's no quick fix，"said Blaisdell．
For a long time，we've believed that people become fat because they are lazy．But this study has proven the opposite to be true as well，which indicates that laziness and obesity are a"vicious cycle （惡性循環(huán)）"．
So，if you constantly feel tired，lacking any urge to get up from your chair，it could be that you've been studying too hard．But you should also pay attention to your diet．
46．During the first three months of the experiment by researchers at the University of California，C．
A．rats from the healthy diet group ate nothing but corn and fish
B．rats on the junk food diet ate more than those on healthy diet
C．rats on the healthy food diet performed better at simple tasks than those on the junk food diet
D．rats on the junk food diet seemed uninterested in sugary food
47．The researchers rewarded thirsty rats with plain water in the lever test toB．
A．help them control their weight
B．test whether fat rats lost interest in the test because they had taken enough sugar
C．change the diet habits of fat rats
D．find out the influence of sugar on rats'brains
48．The underlined word"there"refers toD．
A．a(chǎn)fter the rats on the junk food diet had worked hard to get sugar water
B．a(chǎn)fter the type of food rats prefer had been identified
C．a(chǎn)fter a quick cure for obesity had been found
D．a(chǎn)fter the fact that fatter rats are lazier than lean rats had been found
49．We can conclude from the article thatC．
A．fat people are usually lazier than lean people
B．people should switch between different types of diets to keep healthy
C．being overweight and being lazy can feed into each other
D．laziness is the main cause of weight problems
50．Which of the following is Not Right according to the passage？B
A．Eating junk food can make us fat．
B．Researchers got different results after repeated the tests to fat rats．
C．For a long time，we've believed that people become fat because they are lazy．
D．If you constantly feel tired or study too hard，you need to pay attention to your diet．
分析 本文講述了研究人員通過(guò)在老鼠身上做實(shí)驗(yàn)，結(jié)果表明吃垃圾食品不僅會(huì)使人發(fā)胖，而且還會(huì)使人變懶．
解答 46．C 細(xì)節(jié)理解題．根據(jù)文章第三段Within three months，the rats in the second group were already much fatter than those on the healthy diet．And when researchers trained the rats to do simple tasks，they found even more differences between the two groups rather than weight可知經(jīng)過(guò)三個(gè)月的實(shí)驗(yàn)后，吃垃圾食品的小白鼠已經(jīng)比健康的小白鼠胖了很多；訓(xùn)練簡(jiǎn)單的動(dòng)作，健康的小白鼠也比吃了垃圾食品的小白鼠表現(xiàn)的好，因此答案選C．
47．B 細(xì)節(jié)理解題． 根據(jù)文章第六段第一句But what about the possibility that the fat rats were less passionate about getting sugar water because they were already eating lots of sugar in their daily diet？可知研究者把純凈水給口渴的小白鼠喝，是為了測(cè)試增肥的小白鼠是否已經(jīng)吸收了足夠的糖分而對(duì)實(shí)驗(yàn)已經(jīng)沒(méi)有興趣了．因此答案選B．
48．D 詞義猜測(cè)題． 根據(jù)文意可知吃垃圾食品的小白鼠比之前變得懶惰的事實(shí)被研究者發(fā)現(xiàn)之后，這個(gè)實(shí)驗(yàn)并沒(méi)有結(jié)束，因此答案選D．
49．C 推理判斷題．根據(jù)文章倒數(shù)第二段But this study has proven the opposite to be true as well，which indicates that laziness and obesity are a"vicious cycle （惡性循環(huán)）"可知肥胖后和懶惰后是惡性循環(huán)的，即越胖就會(huì)越懶惰，而越懶惰就會(huì)越胖．因此答案選C．
50．B 細(xì)節(jié)理解題．根據(jù)文章第六段最后一句However，the results came out just the same可知研究者對(duì)吃垃圾食品的小白鼠進(jìn)行測(cè)試的結(jié)果是一致的．所以答案選B．
點(diǎn)評(píng) 本題為研究類(lèi)的閱讀理解．這一題材的閱讀理解是高考�？嫉膬�(nèi)容，對(duì)考生來(lái)說(shuō)有一定的難度，要求考生在通讀全文把握大意的基礎(chǔ)上，結(jié)合具體段落及語(yǔ)境做出正確的選擇．
