单选题 Identical twins are a perfect test case for theories of personality development. If a theory can't explain the differences between identical twins, then it cannot explain environmental effects on personality. Even identical twins brought up in the same home have different personalities.
Take Ladan and Laleh Bijani from Iran. They were identical twins who had spent their entire 29 years joined at the head. And yet, Ladan, the more outspoken of the pair, told journalists, "We are two completely separate individuals, we have different world views, We have different lifestyles, we think very differently about issues." Why did Ladan and Laleh have different personalities?
Self-organized systems in insects can provide us with some ideas. A colony of ants, for example, can be seen as a self-organized system. No supervisor tells the ants what to do, and yet all the jobs get done. The system works in such a way that if one ant carries out a particular job, it be comes less likely that another ant will attempt that job because it no longer needs doing. The result is what economists call "division of labor. "
Self-organization also produces division of labor in human groups. Each individual looks for something to specialize in, his or her own suitable position in the group. If one position is occupied, the individual will seek another. This process increases the differences even between identical twins, because once they've chosen different specialities, a circular mechanism causes small initial differences between them to widen.
Although identical twins look very much alike, people who know them well will distinguish between them. They might, for example, address more questions and comments to one twin than the other—perhaps by chance first. But the consequence is that the twin who is addressed more of ten will do more talking than the other twin, which will cause people who know them to address still more of their questions and comments to that twin. The result, over time, will be one outspoken twin and one quieter one—like Ladan and Laleh Bijani.

单选题 According to the writer we learn that identical twins______.

A. differ in personality
B. differ in appearance
C. have the same lifestyle
D. have the same outlook

单选题 The ant colony is perceived to be well-organized because______.

A. each ant has the duty to help others on a job
B. each ant instinctively fulfills a different task
C. a particular group of ants does a particular job
D. a leading ant monitors the work of working ants

【正确答案】 B

【答案解析】[解析] 细节题。从第三段中提到一个蚂蚁群体可以被看成是一个自我组织系统。没有谁告诉蚂蚁去做什么，但是它们却完成所有工作。在这样一个系统之中，如果一个蚂蚁执行某项工作，另外的蚂蚁不太可能也做这项工作，与选项B“每一个蚂蚁各自完成不同的任务”表示相同的意思，故选B。

单选题 It is said in the text that the working style of ants is characterized by______.

A. shifting roles
B. working shifts
C. division of labor
D. collective efforts

单选题 It can be inferred that the twin' s differences have much to do with______.

A. their chosen lifestyles
B. their respective responsibilities
C. either physical or social factors
D. influences from inside and outside

【正确答案】 D

【答案解析】[解析] 推断题。文中第五段提到其他人与双胞胎交谈等，属于外部影响，而第四段最后一句提到一种循环机制使得他们之间原始的较少的差异逐渐扩大，表明他们自身内部因素也会产生他们之间的不同，所以才会扩大原始的较少差异，可以推断出双胞胎的不同来自外部和内部的影响，故选D。