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[主观题]

The Ebro Delta, in Spain, famous as a battleground during the Spanish Civil War, is now th

e setting for a different contest, one that is pitting rice farmers against two enemies: the rice-eating giant apple snail, and rising sea levels. What happens here will have a bearing on the future of European rice production and the overall health of southern European wetlands.

Located on the Mediterranean just two hours south of Barcelona, the Ebro Delta produces 120 million kilograms of rice a year, making it one of the continent’s most important rice-growing areas. As the sea creeps into these fresh-water marshes, however, rising salinity(盐分)is hampering rice production. At the same time, this sea-water also kills off the greedy giant apple snail, an introduced pest that feeds on young rice plants. The most promising strategy has become to harness one foe against the other.

The battle is currently being waged on land, in greenhouses at the University of Barcelona. Scientists working under the banner “Project Neurice” are seeking varieties of rice that can withstand the increasing salinity without losing the absorbency that makes European rice ideal for traditional Spanish and Italian dishes.

“The project has two sides,” says Xavier Serrat, Neurice project manager and researcher at the University of Barcelona. “the short-term fight against the snail, and a mid- to long-term fight against climate change. But the snail has given the project greater urgency.”

Originally from South America, the snails were accidentally introduced into the Ebro Delta by Global Aquatic Tecnologies, a company that raised the snails for fresh-water aquariums(水族馆), but failed to prevent their escape. For now, the giant apple snail’s presence in Europe is limited to the Ebro Delta. But the snail continues its march to new territory, says Serrat. “The question is not if it will reach other rice-growing areas of Europe, but when.”

Over the next year and a half investigators will test the various strains of salt-tolerant rice they’ve bred. In 2018, farmers will plant the varieties with the most promise in the Ebro Delta and Europe’s other two main rice-growing regions—along the Po in Italy, and France’s Rh?ne. A season in the field will help determine which, if any, of the varieties are ready for commercialization.

As an EU-funded effort, the search for salt-tolerant varieties of rice is taking place in all three countries. Each team is crossbreeding a local European short-grain rice with a long-grain Asian variety that carries the salt-resistant gene. The scientists are breeding successive generations to arrive at varieties that incorporate salt tolerance but retain about 97 percent of the European rice genome(基因组). Why does the author mention the Spanish Civil War at the beginning of the passage?

A.It had great impact on the life of Spanish rice farmers.

B.It is of great significance in the records of Spanish history.

C.Rice farmers in the Ebro Delta are waging a battle of similar importance.

D.Rice farmers in the Ebro Delta are experiencing as hard a time as in the war.

What may be the most effective strategy for rice farmers to employ in fighting their enemies?A.Striking the weaker enemy first

B.Killing two birds with one stone

C.Eliminating the enemy one by one

D.Using one evil to combat the other

What do we learn about “Project Neurice”?A.Its goals will have to be realized at a cost.

B.It aims to increase the yield of Spanish rice.

C.Its immediate priority is to bring the pest under control.

D.It tries to kill the snails with the help of climate change.

What does Neurice project manager say about the giant apple snail?A.It can survive only on southern European wetlands.

B.It will invade other rice-growing regions of Europe.

C.It multiplies at a speed beyond human imagination.

D.It was introduced into the rice fields on purpose.

What is the ultimate goal of the EU-funded program?A.Cultivating ideal salt-resistant rice varieties.

B.Increasing the absorbency of the Spanish rice.

C.Introducing Spanish rice to the rest of Europe.

D.Popularizing the rice crossbreeding technology.

请帮忙给出每个问题的正确答案和分析,谢谢!

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更多“The Ebro Delta, in Spain, famous as a battleground during the Spanish Civil War, is now th”相关的问题

第1题

According to the spokesman of Delta, preferred economy-class tickets_________A. usually ha

According to the spokesman of Delta, preferred economy-class tickets_________

A. usually have a fixed price

B. Can be obtained with additional charge

C. are available 24 hours prior to the plane's departure

D. are only for Medallion members

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第2题

SleepSleep is one of those funny things about being a human being -- you just have' to do

Sleep

Sleep is one of those funny things about being a human being -- you just have' to do it. Have you ever wondered why? And what about the crazy dreams, like the one where a bad per son is chasing you and you can't run or yell. Does that make any sense?

Characteristics of Sleep

When we see someone sleeping, we recognize the following characteristics:

If possible, the person will lie down to go to sleep.

The person's eyes are closed.

The person doesn't hear anything unless it is a loud noise.

The person breathes in a slow, rhythmic pattern.

The person's muscles are completely relaxed. If sitting up, the person may fall out of his or her chair as sleep deepens.

During sleep, the person occasionally rolls over or rearranges his or her body. This happens approximately once or twice an hour. This may be ,the body's way of making sure that no part of the body or skin has its circulation cut off for too long a period of time.

In addition to these outward signs, the heart slows down and the brain does some pretty funky things.

In other words, a sleeping person is unconscious to most things happening in the environment. The biggest difference between someone who is asleep and someone who has fainted or gone into a coma is the fact that a sleeping person can be aroused if the stimulus is strong enough. If you shake the person, yell loudly or flash a bright light, a sleeping person will wake up.

Who Sleeps?

Reptiles(爬行动物), birds and mammals(哺乳动物)all sleep. That is, they become unconscious to their surroundings for periods of time. Some fish and amphibians reduce their aware ness but do not ever become unconscious like the higher vertebrates do. Insects do not appear to sleep, although they may become inactive in daylight or darkness.

By studying brainwaves, it is known that reptiles do not dream. Birds dream a little. Mammals all dream' during sleep.

Different animals sleep in different ways. Some animals, like humans, prefer to sleep in one long session. Other animals like to sleep in many short bursts. Some Sleep at night, while others sleep during the day.

Sleep and the Brain

If you attach an electroencephalograph to a person's head, you can record the person's brainwave activity. An awake and relaxed person generates alpha waves, which are consistent oscillations at about 10 cycles per second. An alert person generates beta waves, which are a bout twice as fast.

During sleep, two slower patterns called theta waves and delta waves take over. Theta waves have oscillations in the range of 3.5 to 7 cycles per second, and delta waves have oscillations of less than 3. 5 cycles per second. As a person falls asleep and sleep deepens, the brain wave patterns slow down. A person deep in delta wave sleep is hardest to wake up.

REM Sleep

At several points during the night, something unexpected happens -- rapid eye movement(REM)sleep occurs. Most people experience three to five intervals of REM sleep per night, and brainwaves during this period speed up to awake levels. If you ever watch a person or a dog experiencing REM sleep, you will see their eyes flickering back and forth rapidly. In many dogs and some people, arms, legs and facial muscles will twitch during REM sleep. Periods of sleep other than REM sleep are known as NREM(non-REM)sleep.

REM sleep is when you dream. If you wake up a person during REM sleep, the person can vividly recall dreams. If you wake up a person during NREM sleep, generally the person .will not be dreaming.

You must have both REM and NREM sleep to get a good night's sleep. A normal person will spend about 25 percent of the night in REM sleep, and the rest in NREM. A REM session -- a dream -- lasts five to 30 minutes.

When You Miss Som

A.Y

B.N

C.NG

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第3题

SleepSleep is one of those funny things about being a human being—you just have to do it.

Sleep

Sleep is one of those funny things about being a human being—you just have to do it. Have you ever wondered why? And what about the crazy dreams, tike the one where a bad person is chasing you and you can't run or yell. Does that make any sense?

Characteristics of Sleep

We all know how sleep looks—when we see someone sleeping, we recognize the following characteristics:

-If possible, the person will lie down to go to sleep.

-The person's eyes are closed.

-The person doesn't hear anything unless it is a loud noise.

-The person breathes in a slow, rhythmic pattern.

-The person's muscles are completely relaxed. If sitting up, the person may fall out of his or her chair as sleep deepens.

-During sleep, the person occasionally rolls over or rearranges his or her body. This happens approximately once or twice an hour. This may be the body's way of making sure that no part of the body or skin has its circulation cut off for too long a period of time.

In addition to these outward signs, the heart slows down and the brain does some pretty frightening things.

In other words, a sleeping person is unconscious to most things happening in the environment. The biggest difference between someone who is asleep and someone who has fainted or gone into a coma is the fact that a sleeping person can be aroused if the stimulus is strong enough. If you shake the person, yell loudly or flash a bright light, a sleeping person will wake up.

For any animal living in the wild, it just doesn't seem very smart to design in a necessary eight-hour period of near-total unconsciousness every day. Yet that is exactly what evolution has done. So there must be a pretty good reason for it!

Who Sleeps?

Reptiles(爬行动物), birds and mammals all sleep. That is, they become unconscious to their surroundings for periods of time. Some fish and amphibians reduce their awareness but do not ever become unconscious like the higher vertebrates(脊椎动物) do. Insects do not appear to sleep, although they may become inactive in daylight or darkness.

By studying brainwaves, it is known that reptiles do not dream. Birds dream a little. Mammals all dream during sleep.

Different animals sleep in different ways. Some animals, like humans, prefer to sleep in one long session. Other animals (dogs, for example) like to sleep in many short bursts. Some sleep at night, while others sleep during the day.

Sleep and the Brain

If you attach an electroencephalograph(脑电图仪) to a person's head, you can record the person's brainwave activity. A waking and relaxed person generates alpha waves, which are consistent vibrations at about 10 cycles per second. An alert person generates beta waves, which are about twice as fast.

During sleep, two slower patterns called theta waves and delta waves take over. Theta waves have oscillations in the range of 3.5 to 7 cycles per second, and delta waves have oscillations of less than 3.5 cycles per second. As a person falls asleep and sleep deepens, the brainwave patterns slow down. The slower the brainwave patterns, the deeper the sleep—a person deep in delta wave sleep is hardest to wake up.

REM Sleep

At several points during the night, something unexpected happens—rapid eye movement (REM) sleep occurs. Most people experience three to five intervals of REM sleep per night, and brainwaves during this period speed up to awake levels. If you ever watch a person or a dog experiencing REM sleep, you will see their eyes flickering back and forth rapidly. In many dogs and some people, arms, legs and facial muscles will twitch(抽搐) during REM sleep. Periods of sleep other than REM sleep are known as NREM (non-REM) sleep.

REM sleep is when you dream, ff

A.Y

B.N

C.NG

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第4题

The stages of sleep take on ____

Sleep is part of a person's daily activity cycle. There are several different stages of sleep, and they too occur in cycles. If you are an average sleeper, your sleep cycle is as follows. When you first drift off into slumber (安睡), your eyes will roll about a bit, your temperature will drop slightly, your muscles will relax, and your breathing were slow and become quite regular. Your brain waves slow down a bit too, with the alpha rhythm of rather fast waves predominating for the first few minutes. This is called stage 1 sleep. For the next half hour or so, as you relax more and more, you will drift down through stage 2 and stage 3 sleep. The lower your stage of sleep, the slower your brain waves will be. Then about 40 to 60 minutes after you lose consciousness you will have reached the deepest sleep of all. Your brain waves will show the large slow waves that are known as the delta rhythm. This is stage 4 sleep. You do not remain at this deep fourth stage all night long, but instead about 80 minutes after you fall into slumber, your brain activity level will increase again slightly. The delta rhythm will disappear, to be replaced by the activity pattern of brain waves. Your eyes will begin to dart around under your closed eyelids (眼皮) as if you were looking at something occurring in front of you. This period of rapid eye movement lasts for some 8 to 15 minutes and is called REM sleep. It is during REM sleep period, your body will soon relax again, your breathing will grow slow and regular once more, and you will slip gently back from stage 1 to stage 4 sleep — only to rise once again to the surface of near consciousness some 80 minutes later.

The stages of sleep take on ____

A) an irregular aspect.

B) a regular aspect

C) a punctual aspect

D) a similar aspect

本题为单选题,请给出正确答案及解析,谢谢!

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第5题

看涨期权的Delta在()之间,看跌期权的Delta在()之间。

A.[0,1];[-1,1]

B.[0,1];[0,1]

C.[0,1];[-1,0]

D.[-1,1];[0,1]

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第6题

当一个投资组合的delta值为()时,我们称之为delta中性。此时,该投资组合的价值不受资产小幅价格波动影响。

A.-1

B.0

C.1

D.0.5

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第7题

The delta is where the rivers ______ and flow into the bay.A.confrontB.convergeC.contendD.

The delta is where the rivers ______ and flow into the bay.

A.confront

B.converge

C.contend

D.contrive

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第8题

According to the spokesman of Delta, preferred economy-class tickets_________A.usually hav

According to the spokesman of Delta, preferred economy-class tickets_________

A.usually have a fixed price

B.Can be obtained with additional charge

C.are available 24 hours prior to the planes departure

D.are only for Medallion members

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第9题

Those portions of the iron-carbon diagram near the delta region and those above ()car

A.2%

B.3%

C.4%

D.5%

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