9．Have you ever thought of why dogs are human's best friends？What's the bond（紧密关系） between human and dogs？A new study by Japanese scientist Miho Nagasawa seems to have found the answer，and it has to do with something named the cuddle（拥抱）chemical．
The cuddle chemical has another，more scientific name oxytocin（催产素）．Oxytocin is something in the blood that encourages bonding．Levels of oxytocin increase，for example，when a mother feeds her newborn baby．According to Nagasawa's study，levels of oxytocin can also go up when we look deeply into the eyes of a dog．
Humans and dogs have been working together for nearly 30，000years．In order to better understand how the cuddle chemical worked between dogs and humans，Nagasawa and his team did an experiment．They tested levels of oxytocin in dogs and humans，and then put them in a room to interact（交流）with each other．While in the room，the humans pet（抚摸）the dogs，spoke to the dogs，and looked into the dogs eyes．Then the scientists tested their levels of oxytocin again．
The researchers found that levels of oxytocin were higher in both humans and dogs after they interacted．However，levels were the highest in the humans and dogs that simply looked into each others eyes，without touch petting or talking．The longer the humans looked into the eyes of the dogs，the more cuddle chemical was let out．Nagasawa did the same experiment with humans and wolves（狼），but it did not give the same results．
30．The underlined word"it"in Paragraph refers toB．
A．something
B．the answer
C．a new study
D．the cuddle chemical
31．Nagasawa did the experiment of humans and dogs to knowA．
A．how oxytocin worked
B．how oxytocin was divided
C．how they helped each other
D．how they interacted with each other
32．Oxytocin levels reached the highest in the humans and dogsC．
A．if the dogs cuddled the humans
B．when they talked with each other
C．when they looked into each other's eyes
D．if the humans pet the dogs
33．What can we infer（推断）from the last sentence of the text？D
A．More experiments are expected to help wolves produce oxytocin．
B．The cuddle chemical in human blood protects us against wolves．
C．It makes sense that humans and wolves are naturally best friends．
D．It's generally impossible to have the bond between humans and wolves．
分析 文章大意：这是一篇说明文，短文主要介绍一项新的研究表明人与狗成为最好的朋友是因为与拥抱化合物（催产素）有关．通过实验发现人与狗交流后，催产素的水平升高．在人与狼之间做了相同的实验，但没有得到相同的结果．狗是人类最好的朋友．这个实验揭秘人和狗之间拥有亲密关系的原因．
解答 30．答案：B．词语猜测题．由上句A new study by Japanese scientist Miho Nagasawa seem to have found the answer（日本科学家长泽美穗的一项新研究似乎找到了答案）可知，and it has to do with something named the cuddle（拥抱）chemical应意为"答案与一种叫拥抱化合物的东西有关"．it代指的是the answer答案．故选B．
31．答案：A．细节理解题．由第二段第一行The cuddle chemical has another，more scientific name：oxytocin（拥抱化合物有另外一个更科学的名字--催产素）及第三段第一行In order to better understand how the cuddle chemical worked between dogs and humans，Nagasawa and his team did an experiment．（为了更好地了解狗与人之间的催产素如何起作用，长泽和他的团队做了一个实验）可知，做实验是为了了解狗与人之间的催产素如何起作用．故选A．
32．答案：C．细节理解题．由第四段第一行However，levels were the highest in the humans and dogs that simply looked into each other's eyes，without much petting or talking．（然而，人与狗仅仅注视，没有抚摸或说话时催产素水平最高）可知，当人与狗注视时催产素水平最高．故选C．
33．答案：D．推理判断题．由文章最后一句Nagasawa did the same experiment with humans and wolves（狼），but it did not give the same results．（长泽在人与狼之间做了同样的实验，但没有给出相同的结果）可知，人与狼之间有紧密关系是不可能的．故选D．
点评 阅读题型，要注重句子与句子之间、段落与段落之间逻辑关系以及对篇章的整体理解．根据所给问题选择正确选项完成试题．
