【正文】 the seagrasses may extend. Although marine botanist W. A. Setchell suggested early on that temperature was critical to the growth and reproduction of eelgrass, it has since been shown that this particularly widespread seagrass grows and reproduces at temperatures between 2 and 4 degrees Celsius in the Arctic and at temperatures up to 28 degrees Celsius on the northeastern coast of the United States. Still, extreme temperatures, in bination with other factors, may have dramatic detrimental effects. For example, in areas of the cold North Atlantic, ice may form in winter. Researchers Robertson and Mann note that when the ice begins to break up, the wind and tides may move the ice around, scouring the bottom and uprooting the eelgrass. In contrast, at the southern end of the eelgrass range, on the southeastern coast of the United States, temperatures over 30 degrees Celsius in summer cause excessive mortality. Seagrass beds also decline if they are subjected to too much exposure to the air. The effect of desiccation is often difficult to separate from the effect of temperature. Most seagrass beds seem tolerant of considerable changes in salinity (salt levels) and can be found in brackish (somewhat salty) waters as well as in full strength seawater.1. According to paragraph 1, which of the following is true about seagrasses in calm ocean waters? A. They will not survive for very long without the nutrients brought In by fastmoving waters.B. They tend to form beds covering large areas along the ocean floor.C. They usually are arranged in separate mounds.D. They grow more slowly than do seagrasses in fastmoving waters.2. According to paragraph 1, which of the following is MOST likely to describe a bed in which seagrasses reach the surface of the water?A. The water is almost pletely still.B. The bed often has major damage from strong waves or currents.C. The bed is generally no more than one square meter in size.D. Grasses form a mosaic of individual mounds.3. Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.A. Light particles and debris collect in some seagrass beds, but are washed out of those affected by strong currents.B. Seagrass beds under the influence of strong currents tend to accumulate many of the lighter particles from other bedsC. The strength of the currents determines how quickly accumulated seagrass debris is moved out of the beds.D. Seagrass debris and other light particles are often moved from areas of strong currents to areas of weak currents.4. The word derive in the passage is closest in meaning toA. maintainB. expelC. obtainD. enrich5. According to paragraph 3, which of the following does NOT accurately describe the sediments that collect in seagrass beds?A. FinegrainedB. Only a few millimeters deepC. Low in oxygenD. Rich in organic matter6. The word confined in the passage is closest in meaning toA. relatedB. limitedC. relevantD. helpful7. According to paragraph 3，how do seagrasses affect the nutrient supply in the ecosystem?A. Because of their high rate of metabolism, they consume a large percentage of the available nutrients.B. They attract various species of algae and bacteria that produce high nutrient concentrations in the water column.C. They take up carbon and other nutrients trapped on the sea bottom and bring them back into use.D. Through anaerobic processes at their roots, they produce a very nutrientrich sediment.8. It can be inferred from paragraph 4 that the reason seagrasses do not grow in very deep water is thatA. they cannot handle intense water pressureB. deep water is too coldC. they would not get enough lightD. deep water is too salty9. The word “detrimental39?！?in the passage is closest in meaning toA. harmfulB. significantC. unexpectedD. distinct10. The word “detrimental39。’ in the passage is closest in meaning toA. harmfulB. significantC. unexpectedD. distinct11. Paragraph 4 suggests that which of the following would be the LEAST likely to cause major damage to eelgrass and other mon seagrasses?A. Factors related to extreme temperaturesB. Exposure to airC. Major changes in salinityD. The movement of ice on the seafloor12. The phrase “tolerant of’ in the passage is closest in meaning toA. unused toB. strongly affected byC. protected fromD. able to withstand13. Look at the four squares [■] that indicate where the following sentence could be added to the passage.Seagrasses grow together in dense patches, or beds, with as many as 4,000 blades per square meter.Where would the sentence best fit? Click on a square [■] to add the sentence to the passage14. Look at the four squares [■] that indicate where the following sentence could be added to the passage.Seagrasses grow together in dense patches, or beds, with as many as 4,000 blades per square meter.Where would the sentence best fit? Click on a square [■] to add the sentence to the passageDrag your answer choices to the spaces where they belong. To remove an answer choice, click on it.To review the passage, click VIEW TEXTSeagrasses are aquatic flowering plants that grow in either sheltered or open areas of the seaA. Seagrass beds are influenced by several physical factors, the most significant being the stability of the sea bottom, which must anchor them against the currents.B. Because they slow currents and waves, seagrass beds collect deposits of rich organic sediments, which are home to many anaerobic microorganisms.C. Unlike sea organisms that depend on the water column for their productivity, seagrasses ensure high rates of productivity by taking nutrients from ocean floor sediment.D. Sediments in seagrass beds vary by region, with temperate beds accumulating sediments from within, and tropical beds c