The radiation that ______blank during the decay of radioactive atomic nuclei is known as gamma radiation.

Generations of mystery and horror ______blank have been influenced by the dark, gothic stories of celebrated American author Edgar Allan Poe (1809–1849).

Gathering accurate data on water flow in the United States is challenging because of the country’s millions of miles of ______blank the volume and speed of water at any given location can vary drastically over time.

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.

To survive when water is scarce, embryos inside African turquoise killifish eggs ______blank a dormant state known as diapause. In this state, embryonic development is paused for as long as two years—longer than the life span of an adult killifish.

When external forces are applied to common glass made from silicates, energy builds up around minuscule defects in the material, resulting in fractures. Recently, engineer Erkka Frankberg of Tampere University in Finland used the chemical ______blank to make a glassy solid that can withstand higher strain than silicate glass can before fracturing.

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.

Photosynthesis, the mechanism by which plants use sunlight to turn carbon dioxide and water into ______blank is fueled in part by an enzyme called Photosystem II that harvests energy-giving electrons from water molecules.

Atoms in a synchrotron, a type of circular particle accelerator, travel faster and faster until they ______blank a desired energy level, at which point they are diverted to collide with a target, smashing the atoms.

In recent years, economists around the world have created new tools that quantify the overall well-being of a country’s citizens. Economists in India, for example, use an Ease of Living Index. This tool ______blank economic potential, sustainability, and citizens’ quality of life.

Sociologist Alton Okinaka sits on the review board tasked with adding new sites to the Hawai‘i Register of Historic Places, which includes Pi‘ilanihale Heiau and the ‘Ōpaeka‘a Road Bridge. Okinaka doesn’t make such decisions ______blank all historical designations must be approved by a group of nine other experts from the fields of architecture, archaeology, history, and Hawaiian culture.

Over twenty years ago, in a landmark experiment in the psychology of choice, professor Sheena Iyengar set up a jam-tasting booth at a grocery store. The number of jams available for tasting ______blank some shoppers had twenty-four different options, others only six. Interestingly, the shoppers with fewer jams to choose from purchased more jam.

Ten of William Shakespeare’s plays are classified as histories. Although each one of these plays, which include Henry V and Richard III, ______blank on a single historical figure (specifically, an English king), some, such as Henry VI Part One and Henry VI Part Two, feature different episodes from the same monarch’s life.     

During the American Civil War, Thomas Morris Chester braved the front lines as a war correspondent for the Philadelphia Press. Amplifying the voices and experiences of Black soldiers ______blank of particular importance to Chester, who later became an activist and lawyer during the postwar Reconstruction period.

Human-made (synthetic) fibers used in clothes and many other consumer products are more durable than most natural plant ______blank the manufacture of synthetic fibers requires toxic chemical solvents that can pollute air and water.