Much new knowledge is admittedly remote from the immediate interests of the ordinary man i

n the street. He is not intrigued or impressed by the fact that a noble gas like xenon can form. compounds—something that until recently most chemists swore was impossible. While even this knowledge may have an impact on him when it is embodied in new technology, until then, he can afford to ignore it. A good bit of new knowledge, on the other hand, is directly related to his immediate concerns, his job, his politics, his family life, even his sexual behavior.

A poignant is the dilemma that parents find themselves in today as a consequence of successive radical changes in the image of the child in society and in our theories of childrearing.

At the turn of the century in the United States, for example, the dominant theory reflected the prevailing scientific belief in the importance of heredity in determining behavior. Mothers who had never heard of Darwin or Spencer raised their babies in ways consistent with the world views of these thinkers. Vulgarized and simplified, passed from person to person, these world views were reflected in the conviction of millions of ordinary people that "bad children are a result of bad stock", that "crime is hereditary", etc.

In the early decades of the century, these attitudes fell back before the advance of environmentalism. The belief that environment shapes personality, and that the early years are the most important, created a new image of the child. The work of Watson and Pavlov began to creep into the public ken. Mothers reflected the new behaviorism, refusing to feed infants on demand, refusing to pick them up when they cried, weaning early to avoid prolonged dependency.

A study by Martha Wolfenstein has compared the advice offered parents in seven successive editions of INFANT CARE, a handbook issued by the United Stats Children's Bureau between 1914 and 1951. She found distinct shifts in the preferred methods for dealing with weaning and thumb-sucking. It is clear from this study that by the late thirties still another image of the child had gained ascendancy. Freudian concepts swept in like a wave and revolutionized childrearing practices. Suddenly, mothers began to hear about "the rights of infants" and the need for "oral gratification". Permissiveness became the order of the day.

The passage tells us that any new knowledge will have a powerful influence on ordinary people if ______.

A．it is simple and understandable

B．it is advocated by eminent persons

C．it has been put into practice and prove tree

D．it bas something to do with their immediate concerns