Verb Forms and Sentence Structure · 30 Questions

Hummingbirds ______ their wings up to about 80 times per second when they hover in front of flowers.

The African Games Co-production Market, one of over 180 annual international conferences supporting video game development, ______ the growth of the African gaming industry by helping start-up studios in Africa find partners.

Beavers cut down small trees with their strong front teeth ______ the branches to build dams across streams.

Scientists believe that homing pigeons can ______ Earth’s magnetic field and use it to find their way home.

In 2008, two years after the death of science fiction writer Octavia Butler, the Huntington Library in ______ received a collection of more than 8,000 items, including Butler’s private notes, research materials, manuscripts, photos, and drawings. Today, the Octavia E. Butler Collection is one of the most researched archives at the library.

When an oxygen tank exploded on Apollo 13 in April 1970, the three astronauts were ______ toward the Moon, about 200,000 miles from Earth.

In 1903, Marie Curie shared the Nobel Prize in Physics with two other scientists ______ the first woman to win a Nobel Prize.

In 1889, Swedish chemist Svante Arrhenius developed an equation to answer a long-standing question: why do chemical reactions speed up at higher temperatures? The Arrhenius equation, named for its creator, ______ an important concept in modern chemistry.

In 1869, Russian chemist Dmitri Mendeleev ______ the known chemical elements into a table that left gaps for elements no one had discovered yet.

Ostriches are the largest living birds. Their wings are much too small to lift their heavy ______ ostriches cannot fly.

Thomas Edison did not ______ the first electric light, but he developed a practical light bulb that could glow for many hours.

In 1953, a fellow performer tripped on legendary jazz musician Dizzy Gillespie’s trumpet, bending its bell upward. When Gillespie tested the damaged instrument, he realized that he ______ sound of a bent bell over that of a straight one.

Each spring, monarch butterflies leave their winter homes in the mountains of central Mexico ______ north toward the United States and Canada.

The Great Barrier Reef, the world’s largest coral reef system, has ______ several mass bleaching events since 1998.

Because a cycle of lunar phases ______ 29.5 days to complete, it’s possible to observe two full moons in a single month, one at the beginning and one at the end.

Since it opened in 1937, the Golden Gate Bridge in San Francisco has ______ one of the most photographed bridges in the world.

Winding through the ice atop Norway’s Jotunheim Mountains is the Lendbreen pass, an ancient route that was used by hunters, farmers, traders, and travelers in the Middle Ages before eventually falling into disuse. Recently, archeologists have ______ knives, horseshoes, wool tunics, and thousands of other artifacts from the icy pass.

A single large oak tree can produce thousands of acorns in one year ______ food for deer, squirrels, and many birds.

The Great Wall of China, built by several dynasties over many centuries, ______ thousands of kilometers across northern China.

Most climbers on Mount Everest spend several weeks getting used to the altitude before they try to reach the ______ climb too quickly is dangerous because the body needs time to adjust to the thin air.

Solarpunk is an art movement that imagines renewable energy–powered technology infused complementarily into nature. In Paolo Bacigalupi’s solarpunk short story “Efficiency,” an artificial intelligence that absorbs sustainable energies, redistributing them through intricate networks of weights and generators, ______ Chicago’s energy grid.

Before 2012, scientists had never ______ a living giant squid in its deep-sea habitat.

An adult human heart beats about 100,000 times a day and ______ blood through roughly 100,000 kilometers of blood vessels.

According to Naomi Nakayama of the University of Edinburgh, the reason seeds from a dying dandelion appear to float in the air while ______ is that their porous plumes enhance drag, allowing the seeds to stay airborne long enough for the wind to disperse them throughout the surrounding area.

Engineers in the Netherlands, a country where about a quarter of the land lies below sea level, are ______ new ways to protect cities from rising water.

Since its launch in 1990, the Hubble Space Telescope has made more than 1.5 million observations ______ scientists measure how fast the universe is expanding.

The artistic talents of Barbara Chase-Riboud, most known for her 1979 historical novel Sally Hemings and the conversation it inspired, ______ limited to the realm of prose: she first excelled in sculpture, where her affinity for bronze—a material she described as “timeless” due to its use across eras and cultures—became part of her artistic identity.

Mercury is the planet closest to the Sun. Its surface can reach about 430°C (800°F) during the ______ hot enough to melt lead.

The James Webb Space Telescope, which observes space in infrared light, can ______ galaxies that formed only a few hundred million years after the big bang.

In the 1970s, Janaki Ammal, a prominent botanist, emerged as a powerful voice in India’s environmental conservation movement. Her exhaustive chromosomal survey of plants in Silent Valley, a pristine tropical forest in Kerala, India, that is home to nearly 1,000 species of native flora (many of which are endangered), ______ instrumental in the government’s decision to preserve the forest.