[单选题]平车分别按普通平车（N）和( )单独统计。-我要搜题网

[多选题]根据事故造成的人员伤亡、直接经济损失、列车脱轨辆数、中断铁路行车时间等情形，事故等级分为特别( )、( )、(　)和一般事故。
A.特大事故
B.重大事故
C.较大事故
D.重特大事故
E.略

[单选题]远动传输通道中断时，供电调度应及时联系通信段，与供电远动检测室技术人员、信息技术所人员共同分析，确定故障范围，如故障确定在（）专业的管辖范围内，供电调度应及时通知供电段（维管段）处理
A.通信
B.供电
C.工务
D.电务

[判断题]积分运算放大器输出端的电阻应该与电容并联。（）
A.正确
B.错误

[不定项选择题]共用题干 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. Dirk Sanders'study centered on how ants______.
A.can manage to thrive in huge numbers
B.defend their resources and territory against other predators
C.attack those invading animals for survival
D.produce such a big impact on the environment

[单选题]平车分别按普通平车（N）和( )单独统计。A.两用平车（NX）B.特殊平车（NX）C.特种平车（NX）D.特种保温车（NX）

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[单选题]平车分别按普通平车（N）和( )单独统计。
A.两用平车（NX）
B.特殊平车（NX）
C.特种平车（NX）
D.特种保温车（NX）