"Cities should plant more street trees. Trees cool hot sidewalks. They soak up rain that would flood the drains. They trap dust thrown up by traffic." What does the first sentence do for the paragraph?

A section on beavers opens: "A dam is a wall of sticks and mud that slows a stream." The four sentences after it explain how such dams change a valley. What does the opening sentence do?

An article argues for later school start times. Paragraph 3 says buses would cost more and practices would end after dark. Paragraph 4 shows two districts that solved both. What does paragraph 3 do?

"Ash trees on Oak Street dropped their leaves in July. Beetle tunnels scarred the bark. Two trees fell in a light wind. The city should take down the rest before a storm does." What does the last sentence do?

An article on rivers ends its flooding section with: "Floods are only one way a river shapes the town around it." The next section is about drinking water. What does that sentence do?

"Solar panels pay off fastest in sunny places. Yet cloudy Milbrook makes more solar power per person than any sunnier town nearby, because its rates reward small rooftop systems." What does the Milbrook sentence do?

"Bridges fall into three families. Beam bridges rest on piers. Arch bridges push their weight outward into stone supports. Suspension bridges hang the road from cables." What job does the first sentence do here?

"When the mill closed, the town lost 300 jobs. Shops on Main Street emptied within a year. The school lost a fifth of its students, and two teachers were let go." What do the last two sentences do for the first?

"Wind turbines need open ridges and steady breezes. Solar farms need flat, sunny ground. Both take up land, but only one keeps working after dark." What does the last sentence do for the passage?

A report's first paragraph describes bikes left across downtown sidewalks. The second describes the racks the city installed and the drop in complaints that followed. What does the second paragraph do?

"First the sap is collected in buckets. Next it is boiled until most of the water leaves. Then the syrup is strained. Finally it is poured into bottles." What does the final sentence do here?

"Permafrost is ground that stays frozen for two years or more. It holds old plant matter. When it thaws, that matter rots and gives off gas. Roads sink as it softens." Which sentence defines the term the rest relies on?

A chapter on hurricanes runs three sections: how storms form, how forecasters track them, and how towns prepare. What does the middle section contribute?

A section begins: "Three things brought the marsh back: a broken dam, patient planting, and a change in the law." The next three paragraphs each take one of them. What does that opening sentence do?

"Some birds copy sounds they hear. One lyrebird in a city park picked up the click of a camera. Other birds copy only the calls of their own kind." What does the middle sentence do?

"The town's buses run half empty. A count last spring found six riders a trip on the north route. A new stop by the clinic could change that." What does the middle sentence do?

An article on bees puts a paragraph about mites right after one on falling hive counts and just before one on new treatments. What does the mites paragraph do?

"A watershed is all the land that drains into one river. Rain on a far hillside can end up in that river. Anything spilled on that land travels with the water." What does the first sentence do for the passage?

"Rust forms where iron meets water and air. Crews paint bridges to keep those two off the metal." The first sentence gives the cause that the action in the second sentence is meant to interrupt.

"Owls hunt at night. Soft fringes on their feathers muffle the sound of their wings. Their wide eyes gather faint light." What do the second and third sentences do for the first sentence?