问题
单项选择题
根据对以往几届世博会上形成参观者排队等候情况的分析，其主要原因是（）等。
A.参观者人数众多、参观门票价格低廉、展馆面积有限
B.参观者人数众多、展馆面积有限、工作人员人手少
C.参观者人数众多、展馆面积有限、受有的展馆特殊展示方式的制约
答案
参考答案：C
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根据对以往几届世博会上形成参观者排队等候情况的分析，其主要原因是（）等。
A.参观者人数众多、参观门票价格低廉、展馆面积有限
B.参观者人数众多、展馆面积有限、工作人员人手少
C.参观者人数众多、展馆面积有限、受有的展馆特殊展示方式的制约
参考答案：C
| It sounds like a science fiction, but researchers say it’s a scientific fact: Microscopic organisms dubbed "killer algae" are paralyzing fish with unknown toxins and then eating away at their flesh. They might be making people sick, too. The name given to this single-cell organism, or dinoflagellate, is Pfiesteria piscimorte—literally, "fish killer." It was discovered at North Carolina State University in 1988, but at the same time, few scientists believed in its existence, much less in its highly unusual predatory nature. But ongoing research has led to international acknowledgment of the phenomenon and, recently, research funding. Seemingly prompted by an unknown substance secreted by fish, the aggressive creature swims into action. It sends neurotoxins into the water and air, paralyzing a fish’s nervous system, and causing it to gasp for air at the surface. Eventually the fish suffocates. The killer dinoflagellate then attaches itself to the fish and begins sucking away at its flesh. This macabre scenario may help solve several sea mysteries, such as why fishermen report seeing "fish walks" (fish trying to leave the water) and pools of dead fish with holes eaten through them. Whether humans are affected by the dinoflagellate’s toxin remains to be seen. Researchers think it’s unlikely eating fresh fish are in danger, but anyone with frequent exposure to the creature could be in peril. Several researchers working with the algae have reported bouts of memory loss and disorientation. To understand the killer algae further, scientists must fully characterize their toxin and determine what stimulates them to attack. They also need to know if the algae are hurting fish populations, and whether pollutants make them more likely to attack. |
The passage is primarily concerned with ______ .
A．informing readers of different sea creatures
B．describing predatory microscopic organisms
C．solving some long-lasting mysteries about the sea
D．discussing the environment for various fishes