问题
单项选择题
运动神经元病是一组病因未明的慢性进行性变性疾病，不侵犯（）
A.脊髓前角细胞
B.脊髓交感神经节细胞
C.脑干运动神经元
D.皮质椎体细胞
E.锥体束
答案
参考答案：B
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运动神经元病是一组病因未明的慢性进行性变性疾病，不侵犯（）
A.脊髓前角细胞
B.脊髓交感神经节细胞
C.脑干运动神经元
D.皮质椎体细胞
E.锥体束
参考答案：B
| Questions 81-90 are based on the following passage. 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. |
It is implied in the passage that ______.
A．many scientists had known dinoflagellate before 1988
B．there had been no such organisms before 1988
C．many scientists were in doubt about the nature of the organism in 1988
D．no scientists knew anything about the organism in 1988