9781422276891

■ ■ Roofers not only construct the roofs of homes and stores, but also those of sports stadiums, such as the National Olympic Sports Complex Stadium in Kiev, Ukraine.

Words to Understand

carcinogenic substances: Those known to cause cancer. historical landmarks: Buildings or other structures that are protected under law because they have special value due to historical, cultural, or other factors. photovoltaic: A type of technology that is used to generate electricity directly from sunlight via an electronic process. solar energy: Energy that is produced by harvesting the heat and energy of the sun.