题目内容
（请给出正确答案）
[单选题]
The technological advances made it possible for the middle classes to enjoy what had once been () only to the very rich.
A.manageable
B.measurable
C.affordable
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00 in fine cotton dress and with exquisite ornaments of bead, gold, and silver. Few burials rival their lavish sepulchres. Being able to trace the development of such rituals over thousands of years has added to our understanding of the development of human intellect and spirit.
［B］ By 40,000 years ago people could be found hunting and gathering food across most of the regions of Africa. Populations in different regions employed various technological developments in adapting to their different environments and climates.
［C］ Archaeological studies have also provided much information about the people who first arrived in the Americas over 12,000 years ago.
［D］ The first fossil records of vascular plants—that is, land plants with tissue that carries food—appeared in the Silurian period. They were simple plants that had not developed separate stems and leaves.
［E］ Laetoli even reveals footprints of humans from 3.6 million years ago. Some sites also contain evidence of the earliest use of simple tools. Archaeologists have also recorded how primitive forms of humans spread out of Africa into Asia about 1.8 million years ago, then into Europe about 900,000 years ago.
［F］ One research project involves the study of garbage in present-day cities across the United States. This garbage is the modern equivalent of the remains found in the archaeological record. In the future, archaeologists will continue to move into new realms of study.
［G］ Other sites that represent great human achievement are as varied as the cliff dwellings of the ancient Anasazi (a group of early Native Americans of North America) at Mesa Verde, Colorado; the Inca city of Machu Picchu high in the Andes Mountains of Peru; and the mysterious, massive stone portrait heads of remote Easter Island in the Pacific.
