39.Our dog Sandy is a golden retriever(尋回犬).Once we performed an experiment to see how keen his nose was.There was one particular pile that must have had hundreds of sticks.We picked up one stick carved an X on it,walked away from the pile and then threw it back into the pile,not once but a dozen times into the pile.It was impossible for us to tell with any certainty which slick we had originally chosen.Each time he brought back that stick,It wasn't the shape or the size or the look of the stick that he used to pick it out from all the others.It was the smell we left on the stick.It is hard to imagine,hut for dogs every living creature has its own distinctive smell. The noses of people have about 5 million cells that sense smell.Dogs' noses have anywhere from 125 to 300 million cells.Moreover,these cells are closer to the surface than cells in our noses,and more active.It has been estimated that dogs such as Sandy have noses that are a million times more sensitive than ours.Clothes that we haven't worn for weeks,and places we've only touched lightly indicate our presence to dogs. His ears are also remarkable.He can hear sounds that humans can't and at distances which are astonishing.It is over our head to know and understand that world.Yet we have the advantage of being able to imagine what his experience is like,though he probably doesn't think too much about how we see the world. The environment is the world that all living things share.Living creatures are born into the environment and are part of it.Yet there is no creature who perceives(感知到)all of what is and what happens.For a dog like Sandy a book isn't much different than a stick,whereas for us one stick is pretty much like every other stick.There is no one world experienced by all living creatures.
(1)Why did the author conduct the experiment?
A.To train Sandy to pick out sticks. B.To show how fast Sandy found sticks. C.To prove sensitivity of Sandy's nose. D.To teach Sandy to tell different smells. (2)What does the author intend to do in paragraph 2?
A.Support the conclusion with numbers. B.Summarize the previous paragraph. C.Provide some advice for the readers. D.Introduce a new topic for discussion. (3)What does the underlined idiom in paragraph 3 mean?
A.Amazing. B.Difficult. C.Reasonable. D.Inconvenient. (4)Which of the following best expresses the authors opinion in the last paragraph?
A.Worlds to experience. B.An environment to share. C.No environment,no creatures. D.One environment,many worlds.