Dogs are known for their sense of smell．They can find missing people and things like bombs and illegal drugs．Now a study suggests that the animal known as man’s best friend can even find bladder（膀胱）cancer．
Cancer cells are thought to produce chemicals with unusual odors（气味）．Researchers think dogs have the ability to smell these odors, even in very small amounts, in urine（尿）．The sense of smell in dogs is thousands of times better than in humans．
The study follows reports of cases where, for example, a dog showed great interest in a growth on the leg of its owner．The man was later found to be skin cancer．Carolyn Willis led a team of researchers at Amersham Hospital in England．They trained different kinds of dogs for the experiment．The study involved urine collected from bladder cancer patients, from people with other diseases and from healthy people．Each dog was tested 8 times．In each test there were 7 samples for the dogs to smell．The dog should signal the one from a bladder cancer patient by lying down next to it．Two cocker dogs were correct 56 percent of the time．But the scientists reported an average success rate of 41 percent．The British Medical Journal published the research．In all, 36 bladder cancer patients and 108 other people took part．During training, all the dogs reportedly even identified（认出）a cancer in a person who had tested healthy before the study．Doctors found a growth on the person’s right kidney（肾）．Carolyn Willis says dogs could help scientists identify the combined chemicals produced by bladder cancer．That information could then be used to develop machines to test for the chemicals．The team also plans to use dogs to help identify markers for other kinds of cancer．
49．What’s the general idea of the text?
A．Dogs have a good sense of smell        B．Dogs can help cure cancer
C．Dogs can smell cancer                 D．Dogs help perform experiments
50．According to the text, people who suffer bladder cancer_____
A．often have urine with unusual smell                       B．probably smoke cigarettes in their life
C．can easily make dogs lie down                    
D．are likely to die within nine years
51．The underlined word “involved” in the text is closest in meaning to _____．
A．showed            B．used          C．proved       D．preferred
52．What can we conclude from the last paragraph?
A．Dogs can only smell bladder cancer．
B．Dogs have a good knowledge of cancer．
C．Cancer doesn’t have any sign in the beginning．
D．Scientists might invent some equipment to test cancer．

Dogs have an understanding of fair play and become angry if they feel that another dog is getting a better deal, a new study has found.

The study looked at how dogs react when a companion is rewarded for the same trick in an unequal way. Friederike Range, a researcher at the University of Vienna in Austria, and her colleagues did a series of experiments with dogs who knew how to respond to the command “give the paw “. The dogs were normally happy to repeatedly give the paw, whether they got a reward or not. But that changed if they saw that another dog was being rewarded with a piece of food, while they received nothing.

“We found that the dogs hesitated significantly longer when obeying the command to give the paw,” the researchers write. The unrewarded dogs eventually stopped cooperating.

Scientists have long known that humans pay close attention to inequity. But researchers always assumed that animals didn’t share the trait. “The argument was that this is a uniquely human phenomenon,” says Frans de Waal, a professor of psychology at Emory University in Atlanta.

That changed in 2003 when he and a colleague did a study on monkeys. The monkeys had to hand a small rock to researchers to get a piece of cucumber in return. They were happy to do this. But if they saw that another monkey was getting a more delicious reward, a grape, for doing the same job, they would throw away the food and rock, and at some point just stopped performing.

In that experiment, the monkeys considered the fairness of two different types of payment. But when Range and her colleagues did a similar study with their trained dogs, testing to see if dogs would become upset if they only got dark bread when other dogs received sausage, they found that as long as the dogs got some kind of food payment, even if it wasn’t the most delicious kind, the animals would play along.

How did the dogs in Range’s study react to the order of “giving the paw”?

A. They took the order even without being rewarded.

B. They took the order only when rewarded.

C. They turned a deaf ear to repeated orders.

D. They hesitated longer when given repeated orders.

The research by Frans De Waal in 2003 ___________.

A. originated from Range’s research on dogs.

B. showed that animals do pay attention to inequity.

C. began the argument that only humans are aware of inequity.

D. was conducted to find out how monkeys reacted to humans’ orders.

Some monkeys in the research become angry because they found another monkey _______.

A. was given less work.

B. was given more food.

C. was given the same type of food.

D. was given more delicious food.

Range found that, compared with monkeys, dogs ____________.

A. care more about whether they are rewarded.

B. care less about what they are rewarded with.

C. care more about what they are ordered to do.

D. care less about who gives them orders.

What is the main idea of the passage?

A. Animals have various ways to show their anger.

B. Dogs are less intelligent than monkeys.

C. Dogs have a sense of fairness.

D. Most animals want to be rewarded equally.

Dogs have a very good ______ of smell and are often used to search for survivors in an earthquake.

A. sense       B. view      C. means       D. idea

 Dogs have a very good ______ of smell and are often used to search for survivors in an earthquake.

A. sense       B. view      C. means       D. idea

Dogs have an understanding of fair play and become angry if they feel that another dog is getting a better deal, a new study has found.
The study looked at how dogs react when a companion is rewarded for the same trick in an unequal way. Friederike Range, a researcher at the University of Vienna in Austria, and her colleagues did a series of experiments with dogs who knew how to respond to the command “give the paw “. The dogs were normally happy to repeatedly give the paw, whether they got a reward or not. But that changed if they saw that another dog was being rewarded with a piece of food, while they received nothing.
“We found that the dogs hesitated significantly longer when obeying the command to give the paw,” the researchers write. The unrewarded dogs eventually stopped cooperating.
Scientists have long known that humans pay close attention to inequity. But researchers always assumed that animals didn’t share the trait. “The argument was that this is a uniquely human phenomenon,” says Frans de Waal, a professor of psychology at Emory University in Atlanta.
That changed in 2003 when he and a colleague did a study on monkeys. The monkeys had to hand a small rock to researchers to get a piece of cucumber in return. They were happy to do this. But if they saw that another monkey was getting a more delicious reward, a grape, for doing the same job, they would throw away the food and rock, and at some point just stopped performing.
In that experiment, the monkeys considered the fairness of two different types of payment. But when Range and her colleagues did a similar study with their trained dogs, testing to see if dogs would become upset if they only got dark bread when other dogs received sausage, they found that as long as the dogs got some kind of food payment, even if it wasn’t the most delicious kind, the animals would play along.
【小题1】How did the dogs in Range’s study react to the order of “giving the paw”?