单选题 {{B}}Passage 4{{/B}}

Animals seem to have the sense to eat when they are hungry and they do not eat more than their bodies need. It has been demonstrated that rats will, when given a choice over a period of time, prefer water with vitamins to water without vitamins even though there is no difference in taste or smell between the two water bottles. When a fragrant flavor was added to the vitamin-enriched fluid, the rats did seem to develop a taste for it and kept drinking it, even after the vitamins were switched to the clear water. In time, however, they broke the habit and went back to where the necessary vitamins were.
In a classic experiment, babies of 6 to 12 months old were placed in a cafeteria feeding arrangement, with a wide selection of baby food before them. They were given whatever food they pointed to or appeared interested in, We are told that at first they showed some unusual eating patterns, but that over a period of time they managed to select well-balanced diet.
So, in selecting food, rats and babies do seem to know and act on what's best for them. Apparently, there is a kind of "body wisdom", which humans soon lose. Most of us do not eat as wisely as we could. Many of our food preferences are culturally determined and influenced by long-established habits. Some people eat foxes, dogs and blackbirds, while we eat cows and pigs. So what people eat and how much they eat seems to be greatly influenced by what is going on around them.

单选题 In the experiment on rats, a fragrant flavor was added to the rat's drinking water to ______.

【正确答案】 C

【答案解析】[解析] 答案在文章第一段第二句：“It has been demonstrated that rats will，when given a choice over a period of time，prefer water with vitamins to water without vitamins even though there is no difference in taste or smell between the two water bottles.”(实践证明，如果在一段时间里让老鼠做出选择，它们更喜欢喝含有维他命的水，虽然两者尝起来和闻起来都没有区别。)

单选题 The expression "the habit" (paragraph 1, sentence 4) refers to drinking water which ______.

【正确答案】 D

【答案解析】[解析] 第一段的最后谈到：“当把香味加到含维生素的液体中时，老鼠便仿佛嗅到了香味并持续喝加了香味的水，即使是维生素转而加到了清水里面也如此。然而，很快，它们就改变了这个习惯，重新开始喝含必需的维生素的水了。”文中的habit实际上指喝有香味的水。所以D是正确答案。

单选题 According to the passage, adults' eating habits differ from those of babies because ______.

A、 adults know better than babies what kind of food are good for their health
B、 adults usually cannot resist the temptation of various delicious foods
C、 adults' eating habits are closely related to the social and cultural customs
D、 adults have more choices of food than babies in eating patterns

【正确答案】 C

【答案解析】[解析] 文章第二段的最后提到：“they managed to select well-balanced diet.”文章第三段提到：“Many of our food preferences are culturally determined and influenced by long-established habits.”由此可推知，成年人和婴儿的饮食习惯的不同点在于；成年人的饮食习惯和他们的社会及文化习俗有关。

单选题 The author implied ih the passage that most of us ______.

【正确答案】 C

【答案解析】[解析] 根据上下文，我们可以知道，文章中并没有提到大多数人都有合理的饮食、选择有营养的食物以及喜欢吃有香味的食品。因此A，B， D都是错误的。文章的最后一句话说：“So what people eat and how much they eat seems to be greatly influenced by what is going on around them.”因此可以断定：我们的饮食习惯受周围环境的影响。C是正确答案。

单选题 As far as their eating habits are concerned, babies and rats are similar in that ______.

【正确答案】 A

【答案解析】[解析] 文章第二段的最后说：“they managed to select well-balanced diet.”第三段的开头说：“So，in selecting food，rats and babies do seem to know and act on what's best for them. Apparently，there is a kind of ’body wisdom'.”因此可以推断：婴儿和老鼠饮食习惯的相同点在于他们都会选择合理的饮食。因此只有A最符合题意。