道题目来自于TPO 8 Running Water on Mars
Paragraph 2: Outflow channels are probably relics of catastrophic flooding on Mars long ago. They appear only in equatorial regions and generally do not form extensive interconnected networks. Instead, they are probably the paths taken by huge volumes of water draining from the southern highlands into the northern plains. The onrushing water arising from these flash floods likely also formed the odd teardrop-shaped “islands” (resembling the miniature versions seen in the wet sand of our beaches at low tide) that have been found on the plains close to the ends of the outflow channels. Judging from the width and depth of the channels, the flow rates must have been truly enormous-perhaps as much as a hundred times greater than the 105 tons per second carried by the great Amazon river. Flooding shaped the outflow channels approximately 3 billion years ago, about the same times as the northern volcanic plains formed.
Question: According to paragraph 2, all of the following are true of the outflow channels on Mars EXCEPT:
A. They formed at around the same time that volcanic activity was occurring on the northern plains.
B. They are found only on certain parts of the Martian surface.
C. They sometimes empty onto what appear to have once been the wet sands of tidal beaches.
D. They are thought to have carried water northward from the equatorial regions.
第二道题目来自于 TPO 16 Planets in Our Solar System
Paragraph 4: Other dimensions along which the two groups differ markedly are density and composition. The densities of the terrestrial planets average about 5 times the density of water, whereas the Jovian planets have densities that average only 1.5 times the density of water. One of the outer planets, Saturn, has a density of only 0.7 that of water, which means that Saturn would float in water. Variations in the composition of the planets are largely responsible for the density differences. The substances that make up both group of planets are divided into three groups-gases, rocks, and ices-based on their melting points. The terrestrial planets are mostly rocks: dense rocky and metallic material, with minor amounts of gases. The Jovian planets, on the other hand, contain a large percentage of the gases hydrogen and helium, with varying amounts of ices: mostly water, ammonia, and methane ices.
Question: Paragraph 4 mentions which of the following as a reason why terrestrial planets are dense?
A. They are made up of three groups of substances.
B. They are composed mainly of rocky and metallic materials.
C. They contain more ice than Jovian planets.
D. They contain relatively small amounts of water.