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问题 选择题

下列各句中，标点符号使用符合规范的一项是[ ]

A．她们听向阳喊我“郑叔”觉得好玩，就朝我喊起“郑…… 叔……”来，大家都开心得大笑。

B．有军事专家对《环球时报》记者说：“美国航母'里根'号来，再次证明中国必须有航母。”

C．两年后的春天，他们又到北山上种了六株树，三株松树，两株云杉，围着一棵河北杨。

D．今年圣诞节，据不完全统计：美国人的圣诞开销预计达4515亿美元，比去年增加3.3%，为近几年之最，美国人仍然过得豪爽。

答案

答案：B

问答题 计算题

某双面磁盘，每面有220道，已知磁盘转速r=3000转/分。数据传输率为175000B/s。求磁盘总容量。
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单项选择题

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.

Researchers think that it is ______.

A. safe to eat fresh fish

B. dangerous to get close to the algae
C. safe to be near the algae

D. dangerous to expose the algae
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