After a spate of illnesses as a child, Wilma Rudolph was told she might never walk again. Defying all odds, Rudolph didn’t just walk, she ______blank the 1960 Summer Olympics in Rome, she won both the 100- and 200-meter dashes and clinched first place for her team in the 4x100-meter relay, becoming the first US woman to win three gold medals in a single Olympics.

On sunny days, dark rooftops absorb solar energy and convert it to unwanted heat, raising the surrounding air ______blank a light-colored covering to an existing dark roof, either by attaching prefabricated reflective sheets or spraying on a paint-like coating, helps combat this effect. 

To serve local families during the Great Depression, innovative New York City librarian Pura Belpré offered storytelling in both English and Spanish, an uncommon ______blank celebrated el Día de los Tres Reyes Magos, an important community holiday; and put on puppet shows dramatizing Puerto Rican folktales.

A subseasonal weather forecast attempts to predict weather conditions three to four weeks in ______blank its predictions are therefore more short-term than those of the seasonal forecast, which attempts to predict the weather more than a month in advance.

In 2018, a team of researchers led by Dr. Caitlin Whalen compiled every available measurement of ocean mixing rates from the past two decades. With this novel data set, the team was able to determine how current-driven mixing varies across ______blank and what impact it has on the distribution of heat and nutrients in the ocean.

In assessing the films of Japanese director Akira Kurosawa, ______blank have missed his equally deep engagement with Japanese artistic traditions such as Noh theater.

As British scientist Peter Whibberley has observed, “the Earth is not a very good timekeeper.” Earth’s slightly irregular rotation rate means that measurements of time must be periodically adjusted. Specifically, an extra “leap second” (the 86,401st second of the day) is ______blank time based on the planet’s rotation lags a full nine-tenths of a second behind time kept by precise atomic clocks.

Professional American football player Fred Cox invented one of the world’s most popular toys. In the 1970s, he came up with the idea for the Nerf football, which ______blank of the harder and heavier regulation football.

In 1966, Emmett Ashford became the first African American to umpire a Major League Baseball game. His energetic gestures announcing when a player had struck out and his habit of barreling after a hit ball to see if it would land out of ______blank transform the traditionally solemn umpire role into a dynamic one.

Working from an earlier discovery of Charpentier’s, chemists Emmanuelle Charpentier and Jennifer Doudna—winners of the 2020 Nobel Prize in Chemistry—re-created and then reprogrammed the so-called “genetic scissors” of a species of DNA-cleaving bacteria ______blank a tool that is revolutionizing the field of gene technology.

When they were first discovered in Australia in 1798, duck-billed, beaver-tailed platypuses so defied categorization that one scientist assigned them the name Ornithorhynchus paradoxus: “paradoxical bird-snout.” The animal, which lays eggs but also nurses ______blank young with milk, has since been classified as belonging to the monotremes group.

Emperor penguins don’t waddle out of the ocean. They launch themselves at such a high speed that they travel up to two meters before landing. How ______blank A layer of microbubbles on their plumage reduces friction as the penguins speed to the surface.

Based on genetic evidence, archaeologists have generally agreed that reindeer domestication began in the eleventh century CE. However, since uncovering fragments of a 2,000-year-old reindeer training harness in northern Siberia, ______blank may have begun much earlier.

In 1903, environmentalist John Muir guided President Theodore Roosevelt on a scenic, sprawling trip through California’s Yosemite Valley. Upon returning from the three-day excursion, Roosevelt ______blank to conserve the nation’s wilderness areas, a vow he upheld for his remaining six years in office.

Archaeologists have estimated that the pre-Columbian Native American city of Cahokia, located across the Mississippi River from modern-day St. Louis, Missouri, had as many as 20,000 inhabitants in the year 1150 ______blank it one of the largest cities in North America at the time.