OG2 阅读 Q51

Choice D is the best answer. In lines 3-6("these...equipment"), the author notes that internal waves “do not ride the ocean surface” but “move underwater, undetectable without the use of satellite imagery or sophisticated monitoring equipment.” The graph shows that the isotherms in an internal wave never reach the ocean’s surface, as the isotherms do not record a depth of 0.
Choice A is incorrect because the graph provides no information about salinity. Choice B is incorrect because the graph shows layers of less dense water (which, based on the passage, are warmer) riding above layers of denser water (which, based on the passage, are cooler). Choice C is incorrect because the graph shows that internal waves push isotherms of warmer water above bands of colder water.