Passage Three Questions 31 to 35 are based on the following passage.
　　There seems never to have been a civilization without toys, but when and how they develop is unknown. They probably came about just to give children something to do. In the ancient world, as is today, most boys played with some kinds of toys and most girls with others. In societies where social roles are rigidly determined, boys pattern their play after the activities of their fathers and girls after the tasks of their mothers. This is true because boys and girls are being prepared, even in play, to step into the roles and responsibilities of the adult world. What is remarkable about the history of toys is not so much how they changed over the centuries but how much they have remained the same. The changes have been mostly in terms of skill, process, and technology. It is the universality of toys with regard to their development in all parts of the world and their persistence to the present that is marvelous. In some African nations, the Americas, China, and Japan, generally the same kinds of toys appeared. Variations depended on local customs and ways of life because toys imitate their surroundings. Nearly every civilization had dolls (玩偶), little weapons, toy soldiers tiny animals and vehicles Because toys can be generally regarded as a kind of art form, they have not been subject to leaps in technology that characterize inventions for adult use. The progress from the wheel to the ox-cart to the automobile is a direct line of upward movement. The progress from a rattle(拨浪鼓) used by a baby in3000 BC to one used by an infant today, however, is not characterized by invention Each rattle is the product of the artistic tastes of the times and subject to the limitations of available materials.