글의 흐름으로 보아, 주어진 문장이 들어가기에 가장 적절한 곳은?The… | [법원직 9급 영어] 12년 1회차 기출문제 상세 페이지

글의 흐름으로 보아, 주어진 문장이 들어가기에 가장 적절한 곳은?
They weren't quite green, however.

Green buildings are not new. For thousands of years, humans have built structures with local natural materials. These structures did not use energy or damage the planet. ( ① ) When the people who lived in them moved on, the structures usually collapsed, and their materials returned to the earth. ( ② ) Before the 1930s, most buildings used far less energy than today's buildings. Instead of air-conditioning, they had windows that opened to let in breezes. ( ③ ) Coal-burning furnaces were used for heating. As a result, many buildings spewed dirty smoke into the air. ( ④ ) Beginning in the 1970s, in the United States and much of the world, air-pollution laws were passed to reduce or eliminate pollution given off by buildings.

①

②

③

④