The pronoun "they" in the second paragraph refers to ..........

The phrase "weary of" is closest in meaning to ...............

The expression “ keep tabs on” is closest meaning to ............

For many people who live in cities, parks are an important part of the landscape. They provide a place for people to relax and play sports, as well as a refuge from the often harsh environment of a city. What people often overlook is that parks also provide considerable environmental benefits. One benefit of parks is that plants absorb carbon dioxide—a key pollutant—and emit oxygen, which humans need to breathe. According to one study, an acre of trees can absorb the same amount of carbon dioxide that a typical car emits in 11,000 miles of driving. Parks also make cities cooler. Scientists have long noted what is called the Urban Heat Island Effect: building materials such as metal, concrete, and asphalt absorb much more of the sun’s heat and release it much more quickly than organic surfaces like trees and grass. Because city landscapes contain so much of these building materials, cities are usually warmer than surrounding rural areas. Parks and other green spaces help to mitigate the Urban Heat Island Effect. Unfortunately, many cities cannot easily create more parks because most land is already being used for buildings, roads, parking lots, and other essential parts of the urban environment. However, cities could benefit from many of the positive effects of parks by encouraging citizens to create another type of green space: rooftop gardens. While most people would not think of starting a garden on their roof, human beings have been planting gardens on rooftops for thousands of years. Some rooftop gardens are very complex and require complicated engineering, but others are simple container gardens that anyone can create with the investment of a few hundred dollars and a few hours of work. Rooftop gardens provide many of the same benefits as other urban park and garden spaces, but without taking up the much-needed land. Like parks, rooftop gardens help to replace carbon dioxide in the air with nourishing oxygen. They also help to lessen the Urban Heat Island Effect, which can save people money. In the summer, rooftop gardens prevent buildings from absorbing heat from the sun, which can significantly reduce cooling bills. In the winter, gardens help hold in the heat that materials like brick and concrete radiate so quickly, leading to savings on heating bills. Rooftop vegetable and herb gardens can also provide fresh food for city dwellers, saving them money and making their diets healthier. Rooftop gardens are not only something everyone can enjoy, they are also a smart environmental investment. 

Based on its use in paragraph 2, it can be inferred that mitigate belongs to which of the following word groups?

According to the passage, great horned owls ..............

The phrase "a resonant hoot" is closest in meaning to ............

The phrase "precious charges" refers to ..............

It takes a long time to raise a family of owlets, so the great horned owl begins early in the year. In January and February, or as late as March in the North, the male calls to the female with a resonant hoot. The female is larger than the male. She sometimes reaches a body length of twenty-two to twenty-four inches, with a wingspread up to fifty inches. To impress her, the male does a strange courtship dance. He bobs. He bows. He ruffles his feathers and hops around with an important air. He flutters from limb to limb and makes flying sorties into the air. Sometimes he returns with an offering of food. They share the repast, after which she joins the dance, hopping and bobbing about as though keeping time to the beat of an inner drum. Owls are poor home builders. They prefer to nest in a large hollow in a tree or even to occupy the deserted nest of a hawk or crow. These structures are large and rough, built of sticks and bark and lined with leaves and feathers. Sometimes owls nest on a rocky ledge, or even on the bare ground. even to occupy the deserted nest of a hawk or crow. These structures are large and rough, built of sticks and bark and lined with leaves and feathers. Sometimes owls nest on a rocky ledge, or even on the bare ground. The mother lays two or three round, dull white eggs. Then she stoically settles herself on the nest and spreads her feather skirts about her to protect her precious charges from snow and cold. It is five weeks before the first downy white owlet pecks its way out of the shell. As the young birds feather out, they look like wise old men with their wide eyes and quizzical expressions. They clamor for food and keep the parents busy supplying mice, squirrels, rabbits, crayfish, and beetles. Later in the season baby crows are taken. Migrating songsters, waterfowl, and game birds all fall prey to the hungry family. It is nearly ten weeks before fledglings leave the nest to search for their own food. The parent birds weary of family life by November and drive the young owls away to establish hunting ranges of their own.

What is the topic of this passage?