单项选择题X 纠错

According to myth, Rwanda’s ancient line of kings descended from a man with secret knowledge: He could (1) ordinary rock into smooth, gleaming iron. (2) this new technology, he taught his people to make hard, durable weapons for defeating their enemies and sharp axes for cutting the forest to make fields. By the time the first Europeans arrived in the 19th century, iron had become (3) in the kingdom of Rwanda.
Other traditional African societies tell stories of (4) ironworkers who descended from heaven or came from other lands. The prevalence of such legends (5) the importance of ironworking in these cultures, and archaeologists have long wondered if the arrival of iron metallurgy (6) the growth of complex early societies. Did foreigners (7) bring ironworking to Africa, or did Africans invent it themselves
Entering the Iron Age was not easy. Metalworkers had to melt ore at (8) temperatures and then repeatedly hammer and reheat the spongy metal. The traditional view is that metallurgists in Turkey were the first to melt iron ore (9) , beginning around 1800 B.C.E. Initially, they (10) the new metal for precious (11) or ritual objects. But by 1200 B.C.E., workers in the Levant were boiling out (12) amounts of iron.
The metal had a major (13) on societies. Iron was a transformative metal. Iron ores are much more (14) than copper or the tin needed to make bronze. Bronze was (15) costly and largely limited (16) use in ritual objects and goods for (17) . But once cultures learned to melt iron, they could put iron tools into the hands of (18) people for clearing forests and tilling the (19) . This boosted agricultural yields, increased the numbers of villages, and (20) ever more social complexity.