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（香的） flavor was added to the vitamin-enriched water, the rats did seem to prefer 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（自助） 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 fox, dog 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．

1．The expression “the habit” （para．1, sentence 4） refers to drinking water which_________．

A．has no smell            B．is tasteless               C．has vitamins            D．is flavored

2．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

3．The author implied in the passage that most of us_________．

A．eat a balanced diet

B．choose the food that is of nutrition

C．have the habits influenced by the surroundings

D． like to eat the food with a fragrant flavor．

4．As far as their eating habits are concerned, babies and rats are similar in that_________．

A．both have the wisdom to choose a balanced diet

B．both prefer flavored food and drink

C．both have the same eating patterns

D．both develop a taste for the same kinds of flavors