| Biological clocks are physiological
systems that enable organisms to live in harmony with the rhythms of nature,
such as the cycles of day and night and of the seasons. Such biological "timers"
exist for almost every kind of periodicity throughout the plant and animal
world, but most of what is known about them comes from the study of circadian,
or daily, rhythms. Circadian rhythms cue typical daily behavior patterns even in
the absence of external cues such as sunrise, demonstrating that such patterns
depend on internal timers for their periodicity. No clock is perfect, however. When organisms are deprived of the hints the world normally provides, they display a characteristic "free-running" period of not quite 24 hours. As a result, free-running animals drift slowly out of phase with the natural world. In experiments in which people are is A. (A) free-running B. (B) rewinding the clock C. (C) light D. (D) changing the temperature [简答题]structural and imported inflation
[填空题]According to physiological theories, dreaming allows us to sort through problems or events of the day that require our attention.
[填空题]Fishes help curb malaria and other mosquito-borne diseases by eating mosquito larvae.
[填空题]Millions of people keep live fishes in home aquariums for biological research.
[单项选择]According to the passage, why do many fishes stay in group ？（）
A. It helps improve their safety. B. It allows them to swim faster. C. It helps them fight their predators. D. It allows them to avoid twists and turns. [单项选择]
Most people do not think of fishes and other sea animals as having voices, and of those who are aware of the fact that many of them can "speak", few understand that these "conversations" have significance. Actually, their talk may be as meaningful as much of our own. For example, some sea animals use their "voices" to locate their food in the ocean expanses (广阔的区域); others use their "voices" to let their fellows know of their locations; and still others, as a means of obtaining mates. Sometimes, "speaking" may even mean the difference between life and death to a sea animal. It appears in some cases that when a predator (食肉动物) approaches, the prey (被捕的动物) depends on no more than the sounds it makes to escape. 我来回答: 提交
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