Fill in the Blanks (Reading & Writing)

Choose the word that best fits each blank.

Cities around the world are increasingly turning to rooftop gardens as a practical response to rising temperatures. When a building's flat roof is covered with soil and plants, the vegetation absorbs sunlight that would otherwise be soaked up by dark surfaces and released as heat. This cooling effect can lower the temperature of the surrounding air, easing the so-called urban heat island that makes city centres noticeably warmer than nearby countryside. Beyond cooling, these green roofs soak up rainwater that would otherwise rush into overwhelmed drains, and they provide habitat for insects and birds in places where greenery is scarce. The chief obstacle remains cost, since older buildings often need structural reinforcement before they can bear the added weight of soil and water.

Rooftop gardens help —reduceintensifymeasure the urban heat island because plants absorb sunlight instead of letting dark surfaces release it as heat, and they also —absorbreleasepollute rainwater that would otherwise flood city drains; their main —obstaclebenefitpurpose is the cost of strengthening older buildings.