Congo's Small Miners Fill Hole Left by Big Businesses(翻译)

commodity – n. something that is bought and sold

cobalt – n. a hard, shiny, silver-white metal that is often mixed with other metals

copper – n. a reddish-brown metal that allows heat and electricity to pass through it easily

battery – n. a device that is placed inside a machine to supply it with power

ore – n. rocks, earth, etc., from which a valuable metal can be taken

cooperative – n. a business or organization that is owned and operated by the people who work there or the people who use its services