A
(2020·东北三省四市高考模拟)
Until last year，Borris would never turn down a pork steak.By the time his owner，Annemarie Formoy，entered him in the PDSA Pet Fit Club competition，he was 28kg—almost double his recommended weight.Thanks to a tailored sixmonth diet and exercise，he is now 7kg lighter.
Borris，at his heaviest，was not alone.The worldwide rate of pet obesity(肥胖症) lies between 22% and 44%.The reasons are fairly predictable.Owners of overweight dogs feed them more snacks and table leftovers，are more likely to have their pets present as they prepare their own meals and are less likely to walk them daily.Owners of obese cats tend to use food as a reward and play with them less.
But obesity also seems to be occurring even in some wild animals that aren't being overfed or underexercised.If these findings are true，something else must be driving obesity and uncovering those could help solve our own problems with the condition.
“Labradors are consistently the headline act when it comes to overweight dogs，” says Eleanor Raffan，a veterinarian and geneticist.She and fellow researchers discovered that a genetic mutation(基因变异) present in around a quarter of Labradors was associated with obesity.For each copy of the mutation—which occurred in a gene called POMC—a dog was about 2kg heavier.Most of the animals the researchers studied had one copy of the mutation，but fewer had two.
“These are dogs always in the kitchen when owners are preparing food，sticking around scouring_a_titbit even if there's not much chance of getting food，or eating disgusting stuff on walks，” Raffan says.“But they're not doing that because it's fun.They're doing it because they're hungry.”
That's because POMC mutations disturb the brain's function of controlling food intake and energy consumption.As a result，the behaviour of these Labradors becomes very foodmotivated.
语篇解读 全球宠物肥胖率在22%到44%之间，弄清楚宠物肥胖的原因对人类应对肥胖问题也很有启发。
1．What is the function of mentioning Borris in the beginning?
A．Stress obesity is common in pets.
B．Show people's love for pets.
C．Reveal pets have a superior lifestyle.
D．Indicate the need for pets to lose weight.
A [考查推理判断。根据第一段内容可知，文章开头提及肥胖的Borris被其主人送去参加宠物健身俱乐部大赛以帮助其减肥，再结合第二段开头的“Borris，at his heaviest，was not alone”可知，Borris并不是个案，由此可推知文章第一段举Borris的例子的作用是强调宠物肥胖很常见。故选A。]
2．How is Paragraph 2 mainly developed?
A．By listing figures.
B．By giving examples.
C．By analyzing causes.
D．By making comparisons.
C [考查写作手法。根据第二段内容，尤其是“The reasons are fairly predictable”可知，本段先指出全球宠物肥胖率在22%到44%之间，然后分析这一现象的原因。故选C。]
3．Why are Labradors ranked first among obese dogs?
A．They tend to be lazy by nature.
B．They all carry POMC genes.
C．Their owners often overfeed them.
D．Many of them have POMC mutations.
D [考查细节理解。根据第四段内容可知，约有四分之一的拉布拉多犬体内的基因变异与肥胖相关。这种变异发生在名为POMC的基因中，该基因每发生一次变异，狗就会增重约2公斤。]
4．Which is closest in meaning to the underlined part in Paragraph 5?
A．Look for something to eat.
B．Take up the kitchen.
C．Get something down.
D．Make up to their owners.
A [考查短语理解。根据倒数第二段内容可知，画线部分所在句是说：这些狗在主人准备食物的时候，经常待在厨房里，四处转悠着寻找吃的，即使没什么机会得到一口吃的，或者在路上捡一些令人作呕的东西吃。由此可知，画线部分的含义应是“寻找吃的”，故选A。]
