单选题What happened to one of the four birds?A It was dead on the way to London.B It flew away from the cage.C It was stolen by someone.

共用题干
第二篇

Night of the Living Ants

When an ant dies,other ants move the dead insect out of the nest.This behavior is interesting to scien-
tists,who wonder how ants know for sure一and so soon一that another ant is dead.
Dong-Hwan Choe,a scientist at the University of California,found that Argentine ants have a chemical
on the outside of their bodies that signals to other ants,"I'm dead一take me away."
But there's a twist to Choe's discovery. These ants behave a little bit like zombies（僵尸）.Choe says
that the living ants一not just the dead ones一have this death chemicals. In other words,while an ant crawls
around,perhaps in a picnic or home,it's telling other ants that it's dead.
What keeps ants from hauling away the living dead? Choe found that Argentine ants have two additional
chemicals on their bodies,and these tell nearby ants something like,"Wait一I'm not dead yet."So Choe's
research turned up two sets of chemical signals in ants:one says,"I'm dead,"the other set says,"I'm not
dead yet."
Other scientists have tried to figure out how ants know when another ant is dead.If an ant is knocked
unconscious,other ants leave it alone until it wakes up.That means ants know that unmoving ants can still be
alive.
Choe suspects that when an Argentine ant dies,the chemical that says"Wait一I'm not dead yet"quickly
goes away. Once that chemical is gone,only the one that says"I'm dead"is left."It's because the dead ant
no longer smells like a living ant that it gets carried to the graveyard（墓地）,not because its body releases
new,unique chemicals after death,"said Choe.When other ants detect the"dead"chemical without the"not
dead yet" chemical,they haul away the body. This was Choe's hypothesis（假设）.
To test his hypothesis,Choe and his team put different chemicals on Argentine ant pupae（蛹）.When
the scientists used the"I'm dead"chemical,other ants quickly hauled the treated pupae away.When the sci-
entists used the"Wait一I'm not dead yet"chemical,other ants left the treated pupae alone.Choe believes
this behavior shows that the" not dead yet" chemical overrides（优先于）the" dead" chemical when picked up
by adult ants.And that when an ant dies,the"not dead yet"chemical fades away.Other nearby ants then de-
tect the remaining"dead"chemical and remove the body from the nest.

The passage"Night of the Living Ants"tells us about_______________.
A:how an ant is moved out of the nest at night
B:what an ant does at night
C:how an ant finds its way in darkness
D:what happens when an ant dies

Some young soldiers who had recently joined the army were being trained in modern ways of fighting,and one of the things they were shown was how an unarmed man could trick an armed enemy and take his weapon away from him．First one of their two instructors took a knife away from the other,using only his bare hands;and then he took a rifle away from him in the same way．After the lesson,and before they went on to train the young soldiers to do these things themselves,the two instructors asked them a number of questions to see how well they had understood what they had been shown．One of the questions was this:“Well,you now know what an unarmed man can do against a man with a rifle．Imagine that you are guarding a bridge at night,and that you have a rifle．Suddenly you see an unarmed enemy soldier coming towards you．What will you do?”
The young soldier who had to answer this question thought carefully for a few seconds before he answered,and then said,“Well,after what I have just seen,I think that the first thing I would do would be to get rid of my rifle as quickly as I could,so that the unarmed enemy couldn't take it from me and kill me with it!”

The ending of the passage is__.

A.serious
B.mysterious
C.curious
D.humorous

Very few of our birds stay with us the year round.Some come to us in the winter from the cold?north.Others come from the south to spend the summer with us.How do they know the way?Suppose?you were told to find your way to a place hundreds of miles away,do you think you could do it?
Yet birds travel over mountains,forests,lakes and even across the oceans,and do not stray from?the path.They find their way back in the spring to the same orchard（果园）and the very trees where?they nested the summer before.
It is wonderful how quickly birds travel such long distances from their summer homes to their?winter ones.Some birds have been known to fly hundreds of miles in a day.But others travel much?more slowly.
Why do birds undertake these long journeys twice a year?Perhaps cold weather and lack of?food drive them from us in the autumn,but we cannot tell why they leave the sunny south to come?back to us in the spring.We know only that many of them like to make their nests and rear their?young in the north.
We are sorry to see them go,but we know that when winter is over they will come back to us.

How far do birds usually travel from their summer homes to their winter ones?

A.About hundreds of miles.
B.About thousands of miles.
C.The distance that takes a bird to fly the whole morning.
D.The passage does not tell us.

共用题干
第二篇

Night of the Living Ants

When an ant dies,other ants move the dead insect out of the nest.This behavior is interesting to scien-
tists,who wonder how ants know for sure一and so soon一that another ant is dead.
Dong-Hwan Choe,a scientist at the University of California,found that Argentine ants have a chemical
on the outside of their bodies that signals to other ants,"I'm dead一take me away."
But there's a twist to Choe's discovery. These ants behave a little bit like zombies（僵尸）.Choe says
that the living ants一not just the dead ones一have this death chemicals. In other words,while an ant crawls
around,perhaps in a picnic or home,it's telling other ants that it's dead.
What keeps ants from hauling away the living dead? Choe found that Argentine ants have two additional
chemicals on their bodies,and these tell nearby ants something like,"Wait一I'm not dead yet."So Choe's
research turned up two sets of chemical signals in ants:one says,"I'm dead,"the other set says,"I'm not
dead yet."
Other scientists have tried to figure out how ants know when another ant is dead.If an ant is knocked
unconscious,other ants leave it alone until it wakes up.That means ants know that unmoving ants can still be
alive.
Choe suspects that when an Argentine ant dies,the chemical that says"Wait一I'm not dead yet"quickly
goes away. Once that chemical is gone,only the one that says"I'm dead"is left."It's because the dead ant
no longer smells like a living ant that it gets carried to the graveyard（墓地）,not because its body releases
new,unique chemicals after death,"said Choe.When other ants detect the"dead"chemical without the"not
dead yet" chemical,they haul away the body. This was Choe's hypothesis（假设）.
To test his hypothesis,Choe and his team put different chemicals on Argentine ant pupae（蛹）.When
the scientists used the"I'm dead"chemical,other ants quickly hauled the treated pupae away.When the sci-
entists used the"Wait一I'm not dead yet"chemical,other ants left the treated pupae alone.Choe believes
this behavior shows that the" not dead yet" chemical overrides（优先于）the" dead" chemical when picked up
by adult ants.And that when an ant dies,the"not dead yet"chemical fades away.Other nearby ants then de-
tect the remaining"dead"chemical and remove the body from the nest.

According to Paragraph 7,what is the result. of the test on Choe's hypothesis?
A:It shows that his hypothesis is wrong.
B:It proves that his hypothesis is convincing.
C:It suggests that his hypothesis needs revising.
D:Not enough evidence has been found to support his hypothesis.

Very few of our birds stay with us the year round.Some come to us in the winter from the cold?north.Others come from the south to spend the summer with us.How do they know the way?Suppose?you were told to find your way to a place hundreds of miles away,do you think you could do it?
Yet birds travel over mountains,forests,lakes and even across the oceans,and do not stray from?the path.They find their way back in the spring to the same orchard（果园）and the very trees where?they nested the summer before.
It is wonderful how quickly birds travel such long distances from their summer homes to their?winter ones.Some birds have been known to fly hundreds of miles in a day.But others travel much?more slowly.
Why do birds undertake these long journeys twice a year?Perhaps cold weather and lack of?food drive them from us in the autumn,but we cannot tell why they leave the sunny south to come?back to us in the spring.We know only that many of them like to make their nests and rear their?young in the north.
We are sorry to see them go,but we know that when winter is over they will come back to us.

In which season do we have most birds to stay with us?

A.In spring.
B.In summer.
C.In winter.
D.We don't know.

Very few of our birds stay with us the year round.Some come to us in the winter from the cold?north.Others come from the south to spend the summer with us.How do they know the way?Suppose?you were told to find your way to a place hundreds of miles away,do you think you could do it?
Yet birds travel over mountains,forests,lakes and even across the oceans,and do not stray from?the path.They find their way back in the spring to the same orchard（果园）and the very trees where?they nested the summer before.
It is wonderful how quickly birds travel such long distances from their summer homes to their?winter ones.Some birds have been known to fly hundreds of miles in a day.But others travel much?more slowly.
Why do birds undertake these long journeys twice a year?Perhaps cold weather and lack of?food drive them from us in the autumn,but we cannot tell why they leave the sunny south to come?back to us in the spring.We know only that many of them like to make their nests and rear their?young in the north.
We are sorry to see them go,but we know that when winter is over they will come back to us.

The underlined part"stray from the path"means__________.

A.lose its way
B.stay on the path
C.keep away from the path
D.fly along the path