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We are aware of the 【potential】 problems.
A. possible B. global C. ongoing D. central
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第一篇
A recent study,published in last week's Journal of American Medical Association,offers a picture of how risky it is to get a lift from a teenage driver. Indeed,a 16-year-old driver with three or more passengers is three times as likely to have a fatal accident as a teenager driving alone,by contrast,the risk of death for drivers between 30 and 59 decreases with. each additional passenger.
The author also found that the death rates for teenage drivers increased dramatically after 10 pm,and especially after midnight.With passengers in the car,the driver was even more likely to die in a late-night accident.
Robert Foss,a scientist at the University of North Carolina Highway safety Research Center, says the higher death rates for teenage drivers,have less to do with"really stupid behavior" than with just a lack of driving experience."The basic issue,"he says,"is that adults who are responsible for issuing licenses fail to recognize how complex and skilled a task driving is."
Both he and the author of the study believe that the way to mitigate（使······缓解）the problem is to have states institute so-called graduated licensing systems,in which getting a license is a multistage process.A graduated license requires that a teenager first prove himself capable of driving in the presence of an adult,followed by a period of driving with passenger restrictions,before graduating to full driving privileges.
Graduate licensing systems have reduced teenage driver crashes,according to recent studies. About half of the states now have some sort of graduated licensing system in place,but only 10 of those states have restrictions on passengers. California is the strictest,with a novice（新手）driver prohibited from carrying any passenger under 20(without the presence of an adult over 25)for the first six months.
According to Paragraph 3,which of the following statements is true?
A:Teenagers should spend more time learning to drive.
B:Driving is a skill too complicated for teenagers to learn.
C:Restriction should be imposed on teenagers applying to take driving lessons.
D:The licensing authorities are partly responsible for teenagers' driving accidents.
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A Health Profile
A health profile is a portrait of all of the factors that influence your health.To draw your health profile,
you will__________(51)what diseases run in your family,what health hazards you may be exposed to
_________(52)work,how your daily__________(53)compares to the recommended standards,how much
timE per week you________(54)exercising and what type of exercise you engage_________(55),how
stressful your work and family environments are,what kinds of illnesses you get regularly,and_______(56)
or not you have any one of a number of addictions._______(57)this portrait,you should have a checkup
to determine how your blood,heart,and lungs are functioning.This checkup will serve________(58)a
haseline,to which you can then comPare later tests.
_________(59)this profile 15 thoroughly drawn,you can begin to think about setting health priorities
based__________(60)your particular portrait.For example,if you drink two martinis every evening,have a
high-stress______(61),are overweight，。moke a pack of cigaretteo a day,and uoe marijuana occaoional-
ly on weekends,you should quit smoking first,followed_________(62)losing the excess weight,reducing
the stress of your job,giving up your marijuana habit,and then finally giving some________(63)to those
martinis if you want to prevent first cancer,and then heart disease.Even for the youthful working person
who has never been sick a day in his life,who 15__________(64)excellent health,a good look at all health
habits and at work and home environments may suggest changes that will_______(65)him in the future.
_________(58)
A:as
B:for
C:on
D:about
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Ants Have Big Impact on Environment as“Ecosystem Engineers”
Research by the University of Exeter has revealed that ants have a big impact on their local environment as a result of their activity as“ecosystem engineers”and predators. The study,published in the Journal of Animal Ecology,found that ants have two distinct effects on their local environment.
Firstly,through moving of soil by nest building activity and by collecting food they af-fect the level of nutrients in the soil. This can indirectly impact the local populations of many animal groups,from decomposers to species much higher up the food chain.
Secondly,they prey on a wide range of other animals,including larger prey which can be attacked by vast numbers of ant workers.
Dirk Sanders,an author of the study from the university's Centre for Ecology and Con-servation,said:“Ants are very effective predators which thrive in huge numbers. They're al-so very territorial and very aggressive,defending their resources and territory against other predators. All of this means they have a strong influence on their surrounding area.”
“In this research,we studied for the first time how big this impact is and the subtleties of it. What we found is that despite being predators,their presence can also lead to an increase in density and diversity of other animal groups. They genuinely play a key role in the local environment,having a big influence on the grassland food web,”Sanders said.
The study,carried out in Germany,studied the impact of the presence of different combinations and densities of black garden ants and common red ants,both species which can be found across Europe,including in the UK.It found that a low density of ants in an area increased the diversity and density of other animals in the local area,particularly the density of herbivores and decomposers. At higher densities ants had no or the opposite effect,showing that predation is counteracting the positive influence.
Dr Frank van Veen,another author on the study,said:“What we find is that the impact of ants on soil nutrient levels has a positive effect on animal groups at low levels,but as the number of ants increases,their predatory impacts have the bigger effect一thereby counteracting the positive influence via ecosystem engineering.”
Ants are important components of ecosystems not only because they constitute a great part of the animal biomass but also because they act as ecosystem engineers. Ant biodiversity is incredibly high and these organisms are highly responsive to human impact,which obviously reduces its richness. However,it is not clear how such disturbance damages the maintenance of ant services to the ecosystem. Ants are important in below ground processes through the alteration of the physical and chemical environment and through their effects on plants,microorganisms,and other soil organisms.
As predators,ants______.
A:prey on small as well as large animals
B: collect nutritious food from the soil
C: collect food as decomposers
D: prey on species much higher up the food chain
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Do we have to wear these name tags?
A: lists
B: forms
C: codes
D: labels
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