Passage Four For some time past it has been widely accepted that babies and other creatures learn to do things because certain acts lead to" rewards"; and there is no reason to doubt that this is true. But it used also to be widely believed that effective rewards, at least in the early stages, had to be directly related to such basic physiological "drives" as thirst or hunger. In other words, a baby would learn if he got food or drink or some sort of physical comfort, not otherwise. It is now clear that this is not so. Babies will learn to behave in ways that produce results in the world with no reward except the successful outcome. Papousek began his studies by using milk in the normal way to "reward" the babies and so teach them to carry out some simple movements, such as turning the head to one side or the other. Then he noticed that a baby who had had enough to drink would refuse the milk but would still go on making the learned response w
A. have the lights turned on
B. be rewarded with milk
C. please their parents
D. be praised
Passage Four
Increasingly, over the past ten years, people -- especially young people have become aware of the need to change their eating habits, because much of the food they eat, particularly processed food, is not good for the health. Consequently, there has been a growing interest in natural foods: foods which do not contain chemical additives and which have not been affected by chemical fertilizers, widely used in farming today.
Natural foods, for example, are vegetables, fruit and grain which have been grown in soil that is rich in organic matter. In simple terms, this means that the soil has been nourished by unused vegetable matter, which provides it with essential vitamins and minerals. This in itself is a natural process compared with the use of chemicals and fertilizers, the main purpose of which is to increase the amount-- but not the quality -- of foods grown in commercial farming areas.
Natural foods also include animals which have be
A. foods containing large quantities of refined flour and vegetables
B. foods with fibers removed
C. foods with more fibers
D. food with additives
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