An urban heat island (UHI) is a metropolitan area that is a lot warmer than the rural areas surrounding it. Heat is created by energy from a...

An urban heat island (UHI) is a metropolitan area that is a lot warmer than the rural areas surrounding it. Heat is created by energy from all the people, cars, buses, and trains in big cities, and (18) __________. There are many reasons for UHIs. When houses, shops, and industrial buildings are constructed close together, it can create a UHI. Building materials are usually very good at insulating, or holding in heat, and this insulation makes the areas around buildings warmer.

Waste heat also contributes to a UHI. People and their tools, such as cars and factories, (19) __________, whether they are jogging, driving, or just living their day to day lives. The energy people burn off usually escapes in the form of heat. Urban areas are densely populated, (20) __________, and they are also densely constructed, meaning buildings are constructed very close together. When there is no more room for an urban area to expand, engineers build upward, creating skyscrapers. All this construction means waste heat, and heat that escapes insulation, has nowhere to go, so it lingers in and between buildings. (21) __________.

Urban heat islands can have worse air and water quality than their rural neighbors, and UHIs contribute to energy demands in the summer, sometimes leading to rolling blackouts. Because of these negative effects, scientists say city dwellers, architects, and designers have to work not only to reduce people’s impact on urban areas, but also (22) __________ that reflect more sunlight and trap less heat.

[Adapted from https://education.nationalgeographic.org]

Question 18:
A. this contributes to the formation of urban heat islands in densely populated, highly active areas
B. the formation of urban heat islands in areas with dense populations and high levels of activity

C. contributed to urban heat island formation in densely populated areas with intense activity
D. which contributes to urban heat island formation in areas with dense populations and high activity

Question 19:
A. are always releasing heat as they operate throughout the city

B. have always burning off energy to perform their work functions

C. are always burning off energy during their various daily activities

D. are always burning off energy, with cars and factories doing so

Question 20:

A. of which the population is large in a small space

B. meaning there are a lot of people in a small space

C. meant that there are a lot of people in a small space

D. and there are a lot of people in a small space

Question 21:

A. By reducing direct exposure to heat stored in urban surfaces, high-rise buildings cause nighttime temperatures in UHIs to fall more gradually during the night

B. Because buildings, sidewalks, and parking lots block heat coming from the ground from rising into the cold night sky, trapping heat on lower levels, and nighttime temperatures in UHIs remain high

C. Nighttime temperatures in UHIs remain high because buildings, sidewalks, and parking lots block heat coming from the ground from rising into the cold night sky, trapping heat on lower levels

D. Trapping heat on high levels, nighttime temperatures in UHIs remain high because buildings, sidewalks, and parking lots block heat coming from the ground from rising into the cold night sky

Question 22:
A. for cooling things down by the use of green roofs and lighter colored materials
B. they must implement the construction of green roofs and use light materials
C. cool things down by using green roofs and lighter colored materials
D. to cool things down by using green roofs and lighter colored materials