There is a reason that prey animals form foraging groups, and that is increased vigilance. An individual redshank is faced with a choice when feeding. It could spend all of its time being vigilant, looking out for approaching ① predators. If it did so, it would certainly significantly reduce the chance that it would be taken by surprise, but it would also ② starve. A bird with its head in the air scanning for predators cannot at the same time have its head down searching for food. In reality of course an individual balances the two behaviors in accordance with the situation in which it finds itself, and as a member of a group it can shift the balance towards ③ feeding. The bigger the flock of birds, the less time an individual bird devotes to ④relaxation. This is possible because the ⑤ presence of many sets of eyes in the flock effectively means that there is always somebody on the look out. 

* vigilance: 경계

How can a design innovate successfully? By                 , always considering the interaction between the new ideas and the current work practice. Consider the history of the word processor. Originally, everyone used typewriters, and typing became the work model users understood. Early word processors stayed close to the typewriter model. They just provided better typing and better correction. Then word processors introduced cut and paste-metaphors taken from the physical operations of cutting with scissors and pasting with glue, something everyone had to do already. These features were an easy extension of the model. Then word processors introduced multiple buffers and multiple documents open at a time, making it easy to share and transfer text across documents. Then they introduced automatic word-wrapping and multiple fonts, and desktop publishing was born. Each step was an easy increment over the previous, and each step walked the user community a little further away from the typewriter model. [3점] 

* increment: 증가 

① taking one step at a time 

② introducing a few constraints 

③ discarding the old for the new 

④ testing new ideas confidentially 

⑤ weakening regulations on technologies

It is important to understand the distinction between energy and power. While units of energy measure the total quantity of work done, they don’t tell us how fast that work is being accomplished. For example, you could lift a one-ton rock up the side of a mountain using only a small electric motor and a system of pulleys, but it would take a long time. A more powerful electric motor could do the job faster, while a still more powerful rocket engine could rapidly propel a payload of identical weight to the top of the mountain in a matter of seconds. Power is therefore defined as the                           . Think of it as energy per unit of time. The standard unit of electrical power is the watt (W). The amount of electrical energy a 10 W light bulb uses depends on how long it is lit: in one hour, it will use 10 Wh of energy. In the same amount of time, a hundred thousand such bulbs would use 1000 kilowatthours (kWh), which equals 1megawatthour (MWh). [3점]

① process of gradually improving a system 

② rate at which energy is produced or used 

③ maximum strength that a machine can exert 

④ capacity to convert electricity to something else 

⑤ possession of control or command over something 

To some participants, the principal value of fair trade lies not in changing the logic of markets but in                           . Unequal terms of trade, protective tariffs, quality standards, and other barriers have long combined to deny farmers in the global South, both small and large, access to profitable consumer markets in the rich nations. At the same time, they watch as their economies are flooded by the dumping of heavily subsidized, impossibly cheap food and consumer products from abroad that undermine their efforts simply to make ends meet. In this view, then, trade justice consists of facilitating access for producers to the Northern markets from which they have traditionally been excluded. This is the stance of many producer groups in the South, some of the Alternative Trading Organizations that work directly with them, some for-profit businesses engaged in fair trade, and many certifying organizations. [3점] 

* tariff: 관세 ** the global South: 제3세계 

① limiting damage to the environment 

② righting the market’s historic injustices 

③ preserving native cultures in the South 

④ demanding corporate investment in agriculture 

⑤ increasing production capacity of disadvantaged producers 

But equally evidently a late-acting lethal will be more stable in the gene pool than an early-acting lethal. 

Any gene exerts its maximum effect on bodies at some particular stage of life, and lethals and semi-lethals are not exceptions. ( ① ) Most genes exert their influence during foetal life, others during childhood, others during young adulthood, others in middle age, and yet others in old age. ( ② ) Obviously lethal genes will tend to be removed from the gene pool. ( ③ ) A gene that is lethal in an older body may still be successful in the gene pool, provided its lethal effect does not show itself until after the body has had time to do at least some reproducing. ( ④ ) For instance, a gene that made old bodies develop cancer could be passed on to numerous offspring because the individuals would reproduce before they got cancer. ( ⑤ ) On the other hand, a gene that made young adult bodies develop cancer would not be passed on to very many offspring, and a gene that made young children develop fatal cancer would not be passed on to any offspring at all. [3점] 

* lethal: 치사 유전자 ** foetal: 태아의