Many butterfly species have bold, brightly colored wings. ______blank some butterfly species have wings that are almost completely colorless and transparent. Glasswing butterflies, for example, have see-through wings that make them nearly invisible.

During a 2021 launch, Rocket Labs’ Electron rocket experienced an unexpected failure: its second-stage booster shut down suddenly after ignition. ______blank instead of downplaying the incident, Rocket Labs’ CEO publicly acknowledged what happened and apologized for the loss of the rocket’s payload, which had consisted of two satellites.

In 1942, the 1,500-mile Alaska Highway was constructed in under nine months, largely due to the skilled work of nearly 4,000 African American soldiers from US Army engineering regiments. The soldiers’ contribution was overlooked for decades. ______blank in 2017, lawmakers declared October 25 a day of recognition—“Alaska Highway Day”—for the troops who helped build this critical roadway.

In 1949, Frank Zamboni developed an ice rink resurfacing machine. As Zamboni’s machine moved along the rink’s surface, it first scraped off the top layer of ice. ______blank it sprayed water into the deep grooves left behind by customers’ skates. Lastly, it smoothed over the newly formed ice.

In the 1850s, William Still was instrumental in helping nearly 1,000 people escape from slavery, earning him the moniker “the Father of the Underground Railroad.” ______blank despite the fame of his contributions during his lifetime, Still is discussed far less today than other prominent Black abolitionists from his era, such as Frederick Douglass and Harriet Tubman.   

Neuroscientist Karen Konkoly wanted to determine whether individuals can understand and respond to questions during REM sleep. She first taught volunteers eye movements they would use to respond to basic math problems while asleep (a single left-right eye movement indicated the number one). ______blank she attached electrodes to the volunteers’ faces to record their eye movements during sleep.

Most conifers (trees belonging to the phylum Coniferophyta) are evergreen. That is, they keep their green leaves or needles year-round. However, not all conifer species are evergreen. Larch trees, ______blank lose their needles every fall.