16.Rats are dirty,cunning and evil-in Chinese culture,at least.But a study published in early December in the journal Science suggests that rats can in fact be helpful,caring animals and can empathize(同情) with their rodent (嚙齒動(dòng)物) friends.
Researchers from the University of Chicago kept two rats together for two weeks so that they could get to know each other.After this,one of the rats was put into a small clear cage,which could be opened from the outside.The other rat was left to run freely outside the cage.
The free rat seemed worried when it saw its friend was trapped.It cireled the eat digging and biting it.After a few days it finally figured out how to open the door.It released its friend and appeared to be excited,running happily after the trapped rat.
Researchers then did the same experiment on more rats.They found that the rats learned to open the cage faster if there was another rat trapped in it than if it was empty.By the end of the experiment,only five out of the 40 rats had learned to open an empty cage.Twenty-three out of 30 rats has learned to open the cage to free another rat.
To test just how"carring"a rat could be,researchers then has the rats choose whether to"rescue"a trapped rat or a piece of chocolate.This time the rats were equally likely to free a rat as they were to free the sweets.Inbal Ben-Ami Bartal led the study."The most shocking thing is they left some of the chocolate for the other rat,"he said.
Scientists have always known that empathy(共鳴)is not unique to humans.It has been proven that apes also feel the emotions of other apcs.However,said Jean Decety,one of the co-authors of the study,"this is the first evidence of helping behavior triggered(激發(fā))by empathy in rats."
49.What is the main point of the first paragraph?B
A.To describe how rats are viewed in Chinese culture.
B.To introduce a new discovery about rats.
C.To prove that people have got the wrong idea about rats.
D.To draw people's attention to rats.
50.What did scientists discover in the experiment?D
A.A free rat was excited when it saw another rat being trapped.
B.Five percent of the rats learned to open an empty cage.
C.Smart rats can learn to release another rat in a few hours.
D.Most rats learned to open the cage to free another rat.
51.When a rat and a piece of chocolate were trapped in different cages,C.
A.the rats outside couldn't decide which to release first
B.more rats wanted to free their friend
C.some of the rats even shared the chocolate with their friend
D.the rats opened the cages faster to free the other rat than to free the chocolate
52.Which of the following statements is TURE?A
A.This is the first time that rats have been found to have empathy.
B.Rats are similar to human beings in many ways.
C.More evidence might be needed to prove this idea.
D.Scientists believe that only humans have empathy.