Night of the Living Ants When an ant dies，other ants move the dead insect out of the nest．

Night of the Living Ants

When an ant dies，other ants move the dead insect out of the nest．This behavior. is interesting to scientists，who wonder how ants know for sure-and so soon-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-take me away．”

But there's a twist to Choe's discovery．Choe says that the living ants-not just the dead ones -have this death chemical．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-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-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 scientists used the“Wait-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(优胜于)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 detect the remaining“dead”chemical and remove the body from the nest．

The phrase“this death chemical”in paragraph 3 refers to

A．the chemical that contains poison．

B．the chemical that announces death．

C．the chemical that prevents death．

D．the chemical that causes death．

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．

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．

"One of the most common house ant species might have been built for living in some of the smallest spaces in a forest, but the ants have found ways to take advantage of the comforts of city living," Purdue University said in a statement. Grzegorz Buczkowski, a Purdue University research assistant professor of entomology, discovered odorous house ants live in supercolonies, creating complex networks entomologists have never seen with the species before now. He found that odorous house ant colonies become larger and more complex as they move from forest to city and act somewhat like an invasive species, the university said. "The ants live about 50 to a colony with one queen in forest settings but explode into supercolonies with more than 6 million workers and 50 000 queens in urban areas," the university explained.

"This is a native species that's doing this," said Buczkowski, whose results are published in the early online version of the journal Biological Invasions. "Native ants are not supposed to become invasive. We don't know of any other native ants that are outcompeting other species of native ants like these," Buczkowski said. Odorous house ants live in hollow acorn shells in the forest. They're called odorous because they have a coconut (椰子)-or rum-like smell when crushed. They're considered one of the most common house ants, Purdue said. In semi-natural areas that are a cross of forest and urban areas, such as a park, Buczkowski said he observed colonies of about 500 workers with a single queen. "It's possible that as the ants get closer to urban areas they have easier access to food, shelter and other resources," he said.

"In the forest, they have to compete for food and nesting sites," Buczkowski said. "In the cities, they don't have that competition. People give them a place to nest, food to eat. " Buczkowski observed the ants in three different settings on and around the Purdue campus. He said it might be expected that if the odorous house ants were able to multiply into complex colonies, other ants would do the same. But Buczkowski found no evidence that other ants had adapted to new environments and evolved into larger groups as the odorous house ants have, Purdie said. "It's possible that odorous house ants are better adapted to city environments than other ant species or that they had somehow outcompeted or dominated other species," he said. "This raises a lot of questions we'd like to answer. " Buczkowski said understanding why the supercolonies form. could lead to better control of the pests in homes, as well as ensuring that they don't outcompete beneficial species.

Future studies on odorous house ants will include studying the ant's genetics and trying to understand the effects of urbanization of odorous house ants, Purdue said.

The word "accommodating" (Line 1, Paragraph 1) is closest in meaning to " ______".

A．helpful

B．easy-going

C．spacious

D．easy to adapt to (a new place)

Many ants forage across the countryside in large numbers and undertake mass

migrations; these activities proceed because one ant lays a trail on the ground for the others

to follow. As a worker ant returns home after finding a source of food, it marks the route

by intermittently touching its stinger to the ground and depositing a tiny amount of trail

(5)pheromone—a mixture of chemicals that delivers diverse messages as the context changes.

These trails incorporate no directional information and may be followed by other ants in

either direction.

Unlike some other messages, such as the one arising from a dead ant, a food trail has to

be kept secret from members of other species. It is not surprising then that ant species use

(10)a wide variety of compounds as trail pheromones. Ants can be extremely sensitive to these

signals. Investigators working with the trail pheromone of the leafcutter ant Atta texana calculated

that one milligram of this substance would suffice to lead a column of ants three times around

Earth.

The vapor of the evaporating pheromone over the trail guides an ant along the way,

(15)and the ant detects this signal with receptors in its antennae. A trail pheromone will

evaporate to furnish the highest concentration of vapor right over the trail, in what is called a

vapor space. In following the trail, the ant moves to the right and left, oscillating from side

to side across the line of the trail itself, bringing first one and then the other antenna into

the vapor space. As the ant moves to the right, its left antenna arrives in the vapor space.

(20)The signal it receives causes it to swing to the left, and the ant then pursues this new course

until its right antenna reaches the vapor space. It then swings back to the right, and so

weaves back and forth down the trail.

What does the passage mainly discuss？

A．The mass migration of ants

B．How ants mark and follow a chemical trail

C．Different species of ants around the world

D．The information contained in pheromones

The smooth operation of an ant colony depends on ten to twenty different signals,

most of which are pheromones (chemical signals triggering behavioral responses). It is

estimated that red fire ants employ at least twelve different chemical signals. The simples

of these is the carbon dioxide from the respiration of an ant cluster, a chemical that acts

(5) a pheromone to promote aggregation. Workers move toward a source of carbon dioxide,

resulting in solitary ants moving to join a group. At the other extreme, the most complex

of the fire ants' signals is probably colony odor, by which the workers of a particular

colony or nest identify another worker as local or foreign. Each ant nest has its own odor

as a result of its location, history, and local food supply. The resident ants pick up this

(10) odor on their bodies, so that ants of the same species, but from different nests, have

different colony odors. This allows ants to identify intruders and maintain colony

integrity.

Fire ants also make use of an alarm pheromone to alert workers to an emergency,

and their scouts lay down a trail pheromone as a guide during mass migrations. A fire ant

(15) queen emits a chemical signal that identifies her to the colony's workers. They respond

by scurrying to gather around her. The decomposing corpse of a dead ant also generates

a signal, to which workers respond by eliminating the corpse from the nest.

Ants provide examples of both public (accessible to other species) and private

messages. One of their most important private messages concerns food, for a food source

(20) is worth keeping secret. Each species marks its trails with signals that are meaningless to

others, so that an ant crossing a trail left by another ant species typically notices nothing.

On the other hand, a secret signal to mark a dead body is unnecessary. Many kinds of ants

perceive a natural decomposition product of dead insects as a signal to remove a corpse.

If an outsider recognizes this message and moves the body, no harm is done.

What aspect of ants does the passage mainly discuss？

A．The relationship between the queen and the worker ants

B．Ways in which ants use chemical signals

C．Methods ants use to identify food sources

D．The importance of respiration in the production of ant pheromones

Kite flying is the sport of sending up into the air, by means of the wind, a light frame. covered with paper, plastic or doth. The frame. can be one of many different shapes and is attached to a long string held in the hand or wound on a drum. Kites have a long history practical application and many different types of kite have been developed to serve various purposes.

The ancient Chinese used bird-kites to carry ropes across rivers and valleys. The current folding kite which will dive excitingly is an improved type of such a kite. With its long flat body and single pair of bird like wings, it looks just like a large bird in the air. The modern version is usually made of tissue paper rather than the traditional silk.

Man-lifting kites were developed in ancient times, again by the Chinese, for getting information from walled cities and army camps. In fact, as recently as World War Ⅱ, German U-boats flew kites from their towers to lift people into the air to watch the land. These kites, which are no longer in existence, were made of lightweight cloth. They were much larger and stronger than the Chinese ones. Their design, however, was simply that of the cutter kite. Smaller in size, this type of kite is still very popular as a toy for children, being easy to make with a diamond-shaped frame, no wings and brown-paper covering.

Box kites are another type of kite found in toy shops today. The first box kite, named for its box-like body, was developed in the 19th century to test theories of flight and this type of cotton-covered kite greatly assisted the success of early airplanes. These kites are the ancestors of a heavier version of the box kite, called the double box kite, which consists of two main sections, placed side by side. Developed for the peacetime purpose of fishing in strong sea wind, it is the only modern kite described which has practical value. A long-lasting plastic material has to be used for this kite, which carries fishing lines.

The ancient Chinese bird-kites were usually made of light frames covered with ______.

A．silk

B．paper

C．cloth

D．plastic

A．protest

B．criticism

C．suggestion

D．fault

A.Right

B.Wrong

C.Not mentioned

Everyone dreams, but some people never recall their dreams, or do so very rarely. Other people always wake up with vivid recollections (记忆) of their dreams, though they forget them very quickly. In an average night of eight hours' sleep, an average adult will dream for around one hundred minutes, probably having three to five dreams, each lasting from ten to thirty minutes.

Scientists can detect when someone is having a dream by using an instrument which measures the electrical waves in the brain. During dreaming, these waves move more quickly. Breathing and pulse rate also increase, and there are rapid eye movements under the lids, just as though the dreamer were really looking at moving objects. These signs of dreaming have been detected in all mammals (哺乳动物) studied, including dogs, monkeys, cats, and elephants, and also some birds and reptiles (爬行动物). This period of sleep is called the “D” state for around 50% of their sleep; the period reduces to around 25% by the age of 10.

Dreams take the form. of stories, but they may be strange and with incidents not connected, which make little sense. Dreams are seldom without people in them and they are usually about people we know. One estimate says that two-thirds of the “cast” of our dream dramas are friends and relations. Vision seems an essential part of dreams, except for people blind from birth. Sound and touch are senses also often aroused, but smell and taste are not frequently involved. In “normal” dreams, the dreamer may be taking part, or be only an observer. But he or she cannot control what happens in the dream.

However, the dreamer does have control over one type of dream. This type of dream is called a “lucid”(清醒的) dream. Not everyone is a lucid dreamer. Some people are occasional lucid dreamers. Others can dream lucidly more or less all the time. In a lucid dream, the dreamer knows that he is dreaming.

Some people dream but cannot remember their dreams.

A．Right

B．Wrong

C．Not mentioned