哪一项是异位妊娠破裂时最主要的症状（） A.停经史和早孕反应 B.不规则 * * 出血 C

质量方针是组织在质量上的（）发展与追求。

A.方向性

B.长远的

C.宏观的

D.细节的

办公厂，自主创业，要具备的素质有[ ]

 ①丰富的专业知识．综合性的知识和技能 ②良好的身体素质和心理素质 ③创新精神 ④诚实劳动，合法经营

A．①②

B．③④

C．①④

D．①②③④

下列哪项不是急性气管-支气管炎的病因（）

A.微生物

B.物理因素

C.化学因素

D.有慢性呼吸道疾病

E.过敏反应

Since the 1930s, the idea that creatures might advertise their " fitness " as mates through symmetry has been around. It rests on the notion that factors ranging from bad genes to coming off worse in too many fights will lead to asymmetries others can see. And over the past few years, experiments with animals and humans seemed to support the idea that symmetry in features such as plumage and facial characteristics influences mate selection.

But no one had actually checked that the animals in these experiments can actually see the subtle differences in symmetry, typically of between 1 and 2 percent. Now the first such experiment has been carried out. The results are worrying for advocates of symmetry detection as a powerful factor in mate selection.

John Swaddle, an ethnologist at the University of Bristol, performed the experiment using wild starlings, which have excellent eyesight. He trained them to hit keys marked with bar patterns with varying levels of asymmetry in order to receive food rewards. This showed the starlings could easily detect asymmetries of between 5 and 10 percent. But at between 1 and 2 percent, their performance plummeted to no better than random guessing.

" This suggests that the levels of asymmetry that birds encounter in nature will often be just too small to be detected, " says Swaddle. He says experiments that linked small asymmetries to fitness may have produced misleading correlations, and says the only direct evidence that birds use asymmetry as a cue to mate fitness involves levels of asymmetry of at least 10 percent. " I think signaling by asymmetry will probably only occur when species show such very large asymmetries—and this doesn’t occur that often. "

This raises questions about research suggesting that humans are influenced by visual asymmetry in their choice of partner. Michael Butt of the Perception Laboratory at the University of St. Andrews, who has carried out such experiments, concedes that no one has ever checked if humans have a threshold to asymmetry detection. He thinks a conclusive test of this would probably involve manipulating complex three-dimensional images: " It would be a very difficult experiment to do "

Burt adds that the abilities of animals to detect asymmetry in bar patterns may not reflect their talent for spotting asymmetries in body shape. " The visibility of an asymmetry may well depend on its type, " he says. Swaddle agrees, and is planning further experiments. " But I suspect that asymmetry is used as a visual cue less often than most people appear to presume, " he warns.

John Swaddle’s experiment suggests that（）

A. asymmetry is seldom big enough

B. fitness may cause incorrect relations

C. birds occasionally rely on symmetry in mate selection

D. random guessing is sometimes as good as asymmetry detection

[说明]
随着计算机技术和通信技术的迅猛发展，计算机网络技术的发展也可用日新月异来形容。在计算机网络的接入技术、光通信技术、路由交换技术、网络安全技术、无线通信技术、网络存储技术等诸多方面不断涌现出各种新技术。在网络规划和设计中，如何根据项目的现状和实际需求，积极地引进和使用新技术，是网络规划设计师的职责。

[问题2]
实现透明的、具有高度生存性的全光通信网是宽带通信网未来发展目标，要实现该目标，需要以下所列举的一些先进技术来支撑。请在以下备选答案中选择相应的选项填入下列空缺处。
光波分多址技术：______； 光突发数据交换技术：______；
副载波多址技术：______； 光时分多址技术：______；
空分光交换技术：______； 无源光网技术：______；
备选答案：
A．该技术多用于接入网部分，以点对多点方式为光线路终端(OLT)和光网络单元(ONU)之间提供光传输媒质
B．该技术是在同一光载波波长上，将时间分割成周期性的帧，每一个帧再分割成若干个时隙，再根据一定的时隙分配原则，使每个ONU在每帧内只按指定的时隙发送信号，然后利用全光时分复用方法在光功率分配器中合成一路光时分脉冲信号，再经全光放大器放大后送入光纤中传输
C．该技术是将光交换元件组成门阵列开关，并适当控制门阵列开关，即可在任一路输入光纤和任一输出光纤之间构成通路
D．该技术是将多个不同波长且互不交叠的光载波分配给不同的ONU，用以实现上行信号的传输，从而产生多路不同波长的光脉冲，然后利用波分复用方法经过合波器形成一路光脉冲信号来共享传输光纤并送入到光交换局
E．该技术的基本原理是将多路基带控制信号调制到不同频率的射频(超短波到微波频率)波上，然后将多路射频信号复用后再去调制一个光载波
F．该技术是针对目前光信号处理技术尚未足够成熟而提出的，有两种光分组技术：包含路由信息的控制分组技术和承载业务的数据分组技术