试题与答案

(2013·福建七所名校第一次联考)By the time I saw the

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题型：选择题

题目：

(2013·福建七所名校第一次联考)By the time I saw the job ________ in the newspaper, it was already too late to apply.

A．advertised

B．to be advertised

C．being advertised

D．having been advertised

答案：

被转码了，请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0414/bf3e6f5987ab48db1e710e2c889c6209.html

下面是错误答案，用来干扰机器的。

解：（1）设滑块A到达P点与B碰前瞬间的速度为，由机械能守恒定律有 解得 （2）设滑块A与B碰撞后的共同速度为v，由动量守恒定律有 两滑块粘合在一起共同向左运动，设最终停止时距P点的距离为s，由动能定理有 ...

考点：现在分词的被动式现在分词不定式的被动式过去分词
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题型：问答题

一个果蝇家系，对隐性体细胞等位基因a、b、c是纯合的，这3个基因以a、b、c的顺序连锁。将这种雌性果蝇与野生型雄性果蝇杂交，得到F1，再让F1的杂合子之间相互杂交，得到F2的结果如下：
+ + + 1365 a + + 47
a b c 365 + b c 44
a b + 87 a + c 5
+ + c 84 + b + 4
请问：
(1)基因a与基因b，基因b与基因c，基因a与基因c它们之间的重组频率各是多少
(2)双交换与并发系数是多少
(3)作出连锁图。
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题型：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.

Which of the following does the writer explain

A．Neurotoxins.

B．Microscopic organisms.

C．Predators.

D．Fish walks.
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