Plants supply o to animals to breathe. 查看更多

 

题目列表(包括答案和解析)

Most people have heard the sound of bees among flowers. Bees live almost everywhere in the world except in the Arctic areas.
Many kinds of agriculture depend on these small, social insects. Without bees, fruit and nut growers as well as many other farmers would not have a crop.
There are more than 20,000 kinds of bees. But only honey bees make enough honey for people to use. Honeybees are highly-organized social insects. They work together in a group, called a colony(群体). Each colony lives in a hive(蜂房). It contains one queen bee -- she lays all the eggs from which the members of the colony come. Each colony has only a few hundred males, called drones. The majority of all bees in a colony are workers, which are all females.
Bees even have a special stomach, called a honey stomach,  which is used to store sweet fluid that the bees gather from flowers. Bees also have long hairs on their body and legs. These hairs capture pollen(花粉) as bees go from flower to flower. Some of the pollen is taken back to the hive. Some, however, is passed to the next flower. This is how many plants are fertilized. Pollen is the reproductive material of plants. Many important agricultural crops depend on bees for fertilization.
Inside their hives, bees store sweet liquid from flowers and pollen as well. They may even gather sweet liquid from some other kinds of insects. These kinds of sweet liquid are also stored in the hive.
Bees make honey through a process. They add liquid from their own mouths to sweet liquid into simple sugar. As the honey is stored, it dries. It becomes thicker and darker.
Although bees are often thought of as honey makers, they provide a surprising number of products. Also, their greatest economic value is in fertilizing crops-not in making honey.
【小题1】The passage is mainly about             .

A.bees and their colony
B.the way for bees to pass pollen
C.bees and agriculture
D.the process for bees to make honey
【小题2】Honeybees are social insects because         .
A.they work in groupsB.there is queen bee in every colony
C.they live in a hiveD.each of them does the same job
【小题3】The most valuable thing honeybees do for people is in             .
A.making honeyB.fertilizing crops
C.making flowers grow betterD.producing pollen
【小题4】The word “fertilize” in the sentence “This is how many plants are fertilized” probably means “    ”.
A.to make plants strong and productive
B.to make soil rich for plants
C.to start the development of young flowers
D.to introduce pollen into plants

查看答案和解析>>

One reaction to all the concern about tropical deforestation(毁林) is a blank stare that asks the question, "Since I don't live there, what does it have to do with me?"

The answer is that your way of life, wherever you live in the world, is tied to the tropics in many ways. If you live in a house, wash your hair, eat fruits and vegetables, drink soda, or drive a car, you can be certain that you are affected by the loss of tropical forests.

Biologically, we are losing the richest regions on earth when, each minute, a piece of tropical forest, the size of ten city blocks, disappears. As many as five million species of plants, animals, and insects (40 to 50 percent of all living things) live there, and are being lost faster than they can be found and described. Their loss is immeasurable.

Take rubber for example. For many uses, only natural rubber from trees will do. Synthetics are not good enough. Today over half the world's commercial rubber is produced in Malaysia and Indonesia, while the Amazon's rubber industry produces much of the world's four million tons. And rubber is an important material in making gloves, balloons, footwear and many sporting goods. Thousands of other tropical plants are valuable for their industrial use.

Many scientists strongly believe that deforestation contributes to the greenhouse effect -- or heating of the earth from increased carbon dioxide in the atmosphere. As we destroy forests, we lose their ability to change carbon dioxide into oxygen.

Carbon dioxide levels could double within the next half-century, warming the earth by as much as 4.5 degrees. The result? A partial melt-down of polar ice caps, raising sea levels as much as 24 feet; even 15 feet could threaten anyone living within 35 miles of the coast. Unbelievable? Maybe. But scientists warn that by the time we realise the severe effects of tropical deforestation, it will be 20 years too late.

Can tropical deforestation affect our everyday lives? Now, you should have got the answer.

1.The underlined word "synthetics" probably means_________.

A. natural rubber                   B. tropical materials

C. man-made material               D. commercial rubber

2.According to the passage, which of the following is NOT true?

A. The forests are losing their function in turning carbon dioxide into oxygen.

B. Many of our daily uses are related to the tropical forests.

C. Tropical plants can be used to make industrial products.

D. High carbon dioxide levels will make the earth warmer.

3.The author's attitude towards the tropical deforestation is _________ .

A. puzzling        B. cold          C. supporting        D. opposed

4.Which of the following might be the best title for the passage?

A. Tropical Forests                 B. The Value of Tropical Forests

C. Tropical Forests and Our Life     D. The Greenhouse Effects

 

查看答案和解析>>

Howard Dill is a giant among giant pumpkin(南瓜) growers. He grew world champion pumpkins for four years running,from 1979 to 1982, and missed winning the fifth year by only 5 pounds. Today, his Dill Atlantic Giant seeds are sold worldwide to more than 50 seed companies. The pumpkins grown from his Dill Atlantic Giant seeds commonly weigh in at over 1,000 pounds. “I don’t have any training in genetics(遗传学); it was all trial and error,” Dill says. He got his love of pumpkins from his father and has enjoyed growing them for years.
Dill still grows giant pumpkins, but not for competition. In the fall, visitors come to enjoy the pumpkins on his 90-acre farm in Nova Scotia, Canada. He plants ten acres of pumpkins for Halloween and two acres of giant pumpkins. One of giant pumpkins was recently baked into 442 pumpkin pies and sold at $5 each for charity.
It you want to try growing a giant pumpkin, Dill recommends starting with a soil test and then adding fertilizer(农药) as needed. Plant the giant pumpkin seed. A giant pumpkin can gain 15 to 20 pounds a day, so careful watering—every day or two—is necessary. You should wait about 130 days until the pumpkin matures and then you can harvest it.
Dill’s favorite pumpkin set the Guinness Book record in 1981. It weighted 493.5 pounds. “I’ve grown them larger since, but that one meant a lot,” he remembers. “I never would have imagined ten
years ago that there would be a 1,000-pounder, but there are many of them now,” says Dill. The 2006 world record holder is Larry Checkon of Pennsylvania. He grew a 1,469 pounder. Dill says, “These world champions are grown from my seeds, so I feel like a winner right along with them.”
【小题1】What can we learn about the world champion pumpkin of 1983?

A.It weighed over 1,000 pounds.
B.It was missing after the competition.
C.It was 5 pounds heavier than that of 1982.
D.It was 5 pounds heavier than Dill’s biggest one that year.
【小题2】 One of Dill’s giant pumpkins earned              .
A.$2210B.$442C.$1000D.$1469
【小题3】 In the third paragraph Dill mainly tells about              .
A.how to do a soil test
B.how to plant the giant pumpkin seed
C.when to water the pumpkin
D.how to grow a giant pumpkin
【小题4】Which of the following is the best title for the passage?
A.Gardening Giant: Howard Dill
B.World Champion Pumpkin
C.Dill Atlantic Giant Seeds
D.How to Grow Giant Pumpkins

查看答案和解析>>

At the heart of the debate over illegal immigration lies one key question: are immigrants good or bad for the economy? The American public overwhelmingly thinks they’re bad. Yet the agreement among most economists is that immigration, both legal and illegal, provides a small net boost to the economy. Immigrants provide cheap labor, lower the prices of everything from farm produce to new homes, and leave consumers with a little more money in their pockets. So why is there such a discrepancy between the perception of immigrants’ impact on the economy and the reality?
There are a number of familiar theories. Some argue that people are anxious and feel threatened by an inflow of new workers. Others highlight the stress that undocumented immigrants place on public services, like schools, hospitals, and jails. Still others emphasize the role of race, arguing that foreigners add to the nation's fears and insecurities. There’s some truth to all these explanations, but they aren’t quite sufficient.
To get a better understanding of what’s going on, consider the way immigration’s impact is felt. Though its overall effect may be positive, its costs and benefits are distributed unevenly. David Card, an economist at UC Berkeley, notes that the ones who profit most directly from immigrants’ low-cost labor are businesses and employers —meatpacking plants in Nebraska, for instance, these producers’ savings probably translate into lower prices at the grocery store, but how many consumers make that mental connection at the checkout counter? As for the drawbacks of illegal immigration, these, too, are concentrated. Native low-skilled workers suffer most from the competition of foreign labor. According to a study by George Borjas, a Harvard economist, immigration has reduced the wages of American high-school dropouts by 9%. 
Among high-skilled, better-educated employees, however, opposition was strongest in states with both high numbers of immigrants and relatively generous social services. What worried them most, in other words, was the financial burden of immigration. That conclusion was reinforced by another finding: that their opposition appeared to soften when that financial burden decreased, as occurred with welfare reform in the 1990s, which curbed immigrants’ access to certain benefits.
The irony is that for all the overexcited debate, the net effect of immigration is minimal. Even for those most acutely affected — say, low-skilled workers, or California residents — the impact isn’t all that dramatic. “The unpleasant voices have tended to dominate our perceptions,” says Daniel Tichenor, a professor at the University of Oregon. “But when all those factors are put together and the economists calculate the numbers, it ends up being a net positive, but a small one.” Too bad most people don’t realize it. 
【小题1】What can we learn from the first paragraph?

A.Whether immigrants are good or bad for the economy has been puzzling economists.
B.The American economy used to thrive on immigration but now it’s a different story.
C.The agreement among economists is that immigration should not be encouraged.
D.The general public thinks differently from most economists on the impact of immigration.
【小题2】What is the chief concern of native high-skilled, better-educated employees about the inflow of immigrants?
A.It may change the existing social structure.
B.It may pose a threat to their economic status.
C.It may decrease .their financial burden.
D.It may place a great pressure on the state budget.
【小题3】What is the irony about the debate over immigration?
A.Even economists can’t reach an agreement about its impact.
B.Those who are opposed to it turn out to benefit most from it.
C.People are making too big a fuss about something of small impact.
D.There is no essential difference between seemingly opposite opinions.
【小题4】Which of the following might be the best title of the passage?
A.A debate about whether to immigrate.
B.A debate about the impact of illegal immigrants.
C.The great impact of immigrants on the economy.
D.Opposition to illegal immigration.

查看答案和解析>>

Global warming is when the earth heats upthe temperature rises.It happens when greenhouse gases—carbon dioxidewater vapornitrous oxide(二氧化氮)and methane(沼气) trap heat and light from the sun in the earth’s atmospherewhich increases the temperature.This is like when heat is trapped in a car.On a very hot daythe car gets hotter when it is out in the parking lot.This is because the heat and light from the sun can get into the carby going through the windowsbut it can’t get back out.Once the light is inside the carit is trapped and the heat builds upjust like it does in the earth’s atmosphere.This is what the greenhouse effect does to the earth.The heat and light can get through the atmospherebut it can’t get out.As a resultthe temperature rises.

Sometimes the temperature can change in a way that helps us.The greenhouse effect makes the earth appropriate for people to live on.Without itthe earth would be freezingor on the other hand it would be burning hot.We would not get the sun’s heat and light to make the night somewhat warm.During the dayespecially during the summerit would be burning because the sun would be up with no atmosphere to filter(过滤) itso peopleplantsand animals would be exposed to all the light and heat.

Although the greenhouse effect makes the earth able to have people living on itif there gets to be too many gasesthe earth can get unusually warmerand many plantsanimalsand people will die.They would die because there would be less food (plants like cornwheatand other vegetables and fruits)This would happen because the plants would not be able to take in the heat.This would cause us to have less food to eatbut it would also limit the food that animals have.Graduallypeopleplantsand animals would all die of hunger.

People are doing many things to try to stop global warming.One thing people are doing is carpooling.Carpooling is driving with someone to a place that you are both going to.This minimizes the amount of greenhouse gases put into the air by a car.

Another thing that people are doing is being more careful about leaving things turned on like the televisioncomputerand the lights.A lot of people are taking time away from the televisionand insteadthey are spending more time outdoors.This helps our planet out a lot.Nowmore people are even riding buseswalking to schooland riding their bikes to lower the amount of greenhouse gases in the air.

Planting trees and recycling also help.If you recycleless trash goes to the dumpand less trash gets burned.As a resultthere are fewer greenhouse gases in our atmosphere.Although adults do many things to help stop global warmingkids can do just as much.

1.By the example given in Paragraph 1the author wants to ________.

Aexplain how greenhouse gases work

Bshow his feeling in a car in hot summer

Ctell us cars are causes of greenhouse gases

Dsay that there are greenhouse gases in every car

2.The underlined word “it” in Paragraph 2 refers to “________”

Alight? Bheat

Ctemperature? Dgreenhouse effect

3.What is the main idea of Paragraph 3?

AIf there is greenhouse effectall the plants will die.

BHuman beings are likely to disappear from the earth.

CCrops can’t take the heat if there is greenhouse effect.

DAlthough greenhouse effect is necessarytoo much of it causes us to die.

4.What will the author most probably discuss in the paragraph that follows?

AWhy cars and buses pollute the air a lot.

BWhat kids can do to help stop global warming.

CWhat global warming is doing to the environment.

DWho should be responsible for the environmental problems.

 

查看答案和解析>>


同步练习册答案