A A．saving them for future use B B．keeping them from rusting C C．letting them grew in value D D．hiding them from locals

A A．highlight the thriftiness of early American colonists B B．illustrate the high status of blacksmiths in that period C C．contrast the attitudes of different civilizations toward nails D D．show the preciousness of nail-making technology at that time

A A．Increased productivity. B B．wider use of new energies. C C．Fierce market competition. D D．reduced cost of raw material.

A A．have undergone many technological improvements B B．have remained basically the same since Roman times C C．are less studied than other everyday product D D．are one of the world’s most significant inventions

A A．cheap technologies bring about revolutionary change. B B．technological innovation is integral to economic success. C C．technology defines people’s understanding of the world. D D．Sophisticated technology developed small inventions.

A A．sharing childcare among community members B B．assigning babies to specific adult categories C C．teaching parenting skills to older children D D．carrying infants around by their parents

A A．an attempt to facilitate intergenerational communication B B．an approach to integrating into western society C C．the conventional parenting style in western culture D D．the differences between western and African ways of living

A A．alleviates parenting pressures B B．consolidates family relationships C C．results in the child-centered family D D．departs from the course of evolution

A A．They tend to fall short of official requirements. B B．They have difficulty finding enough caregivers. C C．They ought to improve their career-to-child ratio. D D．They should try to prevent parental depression.

A A．Instructive teaching: a dilemma for anxious parents. B B．For a happier family learn from the hunter gatherers. C C．Mixed-aged playgroup, a better choice for lonely children. D D．Tracing the history of parenting: from Africa to Europe.