良性高血压的病理变化有（） A.颗粒性固缩肾 B.细动脉纤维素样变性 C.细动脉玻璃

分解因式：3a²b-4ab=（    ）。

数吨牛肉在速冻冷藏前，进行卫生质量抽样检查，检出埃希菌属细菌，说明该批牛肉

A．二级新鲜度
B．即将腐败，应限期出售
C．受到肠道致病菌的严重污染
D．受到粪便的近期污染
E．食品清洁状态不良

男性青年，因车祸致胫腓骨中上1／3处开放性粉碎性骨折，行彻底清创术，摘除所有的粉碎的骨折片，术后行牵引治疗8个月后，骨折仍未愈合，其最可能的原因是

A．清创时摘除了过多的碎骨片

B．未做内固定

C．伤肢固定不确切

D．功能锻炼不够

E．骨折处血液供应差

阅读理解。

     People diet to look more attractive. Fish diet to avoid being beaten up, thrown out of their social group,

and getting eaten as a result. That is the fascinating conclusion of the latest research into fish behavior by

a team of Australian scientists.

     The research team have discovered that subordinate fish voluntarily diet to avoid challenging their larger

competitors. "In studying gobies we noticed that only the largest two individuals, a male and female, had

breeding (繁殖) rights within the group," explains Marian Wong. "All other group members are nonbreeding

females, each being 5-10% smaller than its next largest competitor. We wanted to find out how they

maintain this precise size separation."

     The reason for the size difference was easy to see. Once a subordinate fish grows to within 5-10% of

the size of its larger competitor, it causes a fight which usually ends in the smaller goby being driven away

from the group. More often than not, the evicted fish is then eaten up.

     It appeared that the smaller fish were keeping themselves small in order to avoid challenging the boss

fish. Whether they did so voluntarily, by restraining how much they ate, was not clear. The research team

decided to do an experiment. They tried to fatten up some of the subordinate gobies to see what happened.

To their surprise, the gobies simply refused the extra food they were offered, clearly preferring to remain

small and avoid fights, over having a feast.

     The discovery challenges the traditional scientific view of how boss individuals keep their position in a

group. Previously it was thought that large individuals simply used their weight and size to threaten their

subordinates and take more of the food for themselves, so keeping their competitors small.

     While the habits of gobies may seem a little mysterious, Dr. Wong explains that understanding the

relationships between boss and subordinate animals is important to understanding how hierarchical (等级的)

societies remain stable.

     The research has proved the fact that voluntary dieting is a habit far from exclusive to humans. "As

yet, we lack a complete understanding of how widespread the voluntary reduction of food intake is in

nature," the researchers comment. "Data on human dieting suggests that, while humans generally diet to

improve health or increase attractiveness, rarely does it improve long-term health and males regularly

prefer females that are fatter than the females' own ideal."

1. When a goby grows to within 5-10% of the size of its larger competitor, it _____.

A. faces danger

B. has breeding rights

C. eats its competitor

D. leaves the group itself

2. The underlined words "the evicted fish" in Paragraph 3 refer to _____.

A. the fish beaten up

B. the fish found out

C. the fish fattened up

D. the fish driven away

3. The experiment showed that the smaller fish _____.

A. fought over a feast

B. went on diet willingly

C. preferred some extra food

D. challenged the boss fish

4. What is the text mainly about?

A. Fish dieting and human dieting.

B. Dieting and health.

C. Human dieting.

D. Fish dieting.

自动喷水灭火系统每个报警阀组控制的最不利点喷头处，应设未端试水装臵、其它防火分区、楼层均应设直径为（）mm的试水阀。