As distinct from common dogs, wolves are self-sufficient predators that thrive without human support and can effectively locate their own sources of food.

The human eye is a relatively recent development of nature—it evolved from the eyes of earlier primates, which had in turn evolved over many generations from the primitive eyes of the pre-mammalian synapsids, which had themselves previously evolved from the simple photoreceptors of our common single-celled ancestors.

With steel, oil, and aluminum prices being high enough so any major construction effort would be prohibitively expensive, contractors across the country found themselves unemployed.

In May 2003, a series of five granite ledges on the side of Cannon Mountain, known as “The Old Man of the Mountain,” collapsed in the middle of the night due to centuries of repeated freezing and thawing, which opened a fissure in it so large that the stone became unstable and the formation detached from the cliff face.

In May 2003, a series of five granite ledges on the side of Cannon Mountain, known as “The Old Man of the Mountain,” collapsed in the middle of the night due to centuries of repeated freezing and thawing, which opened a fissure in it so large that the stone became unstable and the formation detached from the cliff face.

According to the passage, the appearances of Ojos del Salado and Llullaillaco might change rapidly compared to other peaks because they are distinctive with regard to which of the following factors?

According to the passage, which of the following contributed to Simón Bolívar’s success?

The passage suggests that many Latin Americans looked on European and North American revolutions in which of the following ways?

The author of the passage would be most likely to make which of the following recommendations to scholars of Latin American history?

The passage provides information in support of which of the following assertions?

It can be inferred from the passage that which of the following is true of arboreal spiders that make heavy use of web hunting?

It can be inferred from the passage that which of the following is a true statement about Dolomedes?

Describing her proposal for returning the nearly bankrupt university to solvency, the new chancellor’s ideas were detailed on Monday for addressing the school’s alarming deficit by raising more than $75 million in alumni donations over the next five years.

It is often mistaken for a continent, but icy Greenland is actually the largest island in the world, which belongs geologically to North America’s tectonic plate.

Virologists, having learned an enormous amount during the last two decades about HIV/AIDS and its devolution from a fatal to manageable disease, are now learning more details about how the virus changes and how patients transmit the disease.

Unlike the belief accepted by many of his fellow physicists that electrical resistance increases continuously when magnetic forces are applied, Klaus von Klitzing made new observations of how electrical resistance rises in a series of discrete steps at the quantum level, and in 1985, at the age of 42, won the Nobel Prize in Physics for his discovery of an extremely precise measure for determining electrical resistance.

Igor Stravinsky’s familiarity with the music and folklore of Russia, France, and that of England were essential to his development as a composer, underpinning both his modern sensibility as much as his major works.

Which of the following most logically completes the passage?

Carbon dioxide emissions are a concern for environmentalists, but another category, hydroflourocarbons (or HFCs), is among the lesser-known types of greenhouse gas. A study of refrigerant gases showed that HFCs decompose into harmless compounds relatively quickly. Therefore, if HFCs were banned, the level of greenhouse gas pollution would be greatly reduced, especially since _______.

Despite the near-total eradication of the formerly commonplace measles, it is so devastating that even minor outbreaks have become a historic health crisis for afflicted areas.

People all over the world cultivate plants for food and for sale, but a surprising consequence of selective breeding has been the alteration of fruits and vegetables, and, after many generations, they are changed significantly in taste and appearance.