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____time based on the planet’s rotation lags a full nine-tenths of a second behind time kept by precise atomic clocks.

Which choice completes the text so that it conforms to the conventions of Standard English?

A) added whenever

B) added. Whenever

C) added; whenever

D) added, whenever

The intense pressure found in the deep ocean can affect the structure of proteins in fish’s cells, distorting the proteins’ shape. The chemical trimethylamine N-oxide (TMAO) counters this effect, ensuring that proteins retain their original____is found in high concentrations in the cells of the deepest-dwelling fish.

Which choice completes the text so that it conforms to the conventions of Standard English?

A) configurations TMAO

B) configurations, TMAO

C) configurations and TMAO

D) configurations. TMAO

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.

Which choice completes the text so that it conforms to the conventions of Standard English?

A) California,

B) California

C) California:

D) California-

In her two major series “Memory Test” and “Autobiography,” painter Howardena Pindell explored themes____healing, selfdiscovery, and memory by cutting and sewing back together pieces of canvas and inserting personal artifacts, such as postcards, into some of the paintings.

Which choice completes the text so that it conforms to the conventions of Standard English?

A) of,

B) of-

C) of

D) of;

While many video game creators strive to make their graphics ever more____others look to the past, developing titles with visuals inspired by the “8-bit” games of the 1980s and 1990s. (The term “8-bit” refers to a console whose processor could only handle eight bits of data at once.)

Which choice completes the text so that it conforms to the conventions of Standard English?

A) lifelike but

B) lifelike

C) lifelike, but

D) lifelike,

Beatrix Potter is perhaps best known for writing and illustrating children’s books such as The Tale of Peter Rabbit (1902), but she also dedicated herself to mycology, the study of____more than 350 paintings of the fungal species she observed in nature and submitting her research on spore germination to the Linnean Society of London.

Which choice completes the text so that it conforms to the conventions of Standard English?

A) fungi. Producing

B) fungi producing

C) fungi, producing

D) fungi; producing

Eli Eisenberg, a genetics expert at Tel Aviv University in Israel, recently discovered that____have a special genetic ability called RNA editing that confers evolutionary advantages.

Which choice completes the text so that it conforms to the conventions of Standard English?

A) cephalopods—ocean dwellers that include the squid, the octopus, and the cuttlefish—

B) cephalopods, ocean dwellers that include: the squid, the octopus, and the cuttlefish,

C) cephalopods—ocean dwellers—that include the squid, the octopus, and the cuttlefish,

D) cephalopods, ocean dwellers that include the squid, the octopus, and the cuttlefish.

Seneca sculptor Marie Watt’s blanket art comes in a range of shapes and sizes. In 2004, Watt sewed strips of blankets together to craft a 10-by-13-inch____in 2014, she arranged folded blankets into two large stacks and then cast them in bronze, creating two curving 18-foot-tall blue-bronze pillars.

Which choice completes the text so that it conforms to the conventions of Standard English?

A)sampler later,

B) sampler;

C) sampler,

D) sampler, later

Humans were long thought to have begun occupying the Peruvian settlement of Machu Picchu between 1440 and 1450 CE.However, a team led by anthropologist Dr. Richard Burger used accelerator mass spectrometry to uncover evidence that it was occupied____1420 CE, according to Burger, humans were likely inhabiting the area.

Which choice completes the text so that it conforms to the conventions of Standard English?

A) earlier, which in

B) earlier. In

C) earlier in

D) earlier, in

It is generally true that technological change is a linear process, in which once-useful technologies are replaced by new and better____the reawakening of interest in the steam engine (from advocates of carbon-neutral rail travel) reminds us that ostensibly obsolete technologies may be brought back into service to address society’s changing needs.

Which choice completes the text so that it conforms to the conventions of Standard English?

A) ones; even so,

B) ones even so,

C) ones, even so,

D) ones, even so;