6英语XQ试题)
DCaribbean box jcllyfish()can learn to spot and avoid obstaces(despite lackingacentral brain,accordin esyThifirst vidne that jellyfish an domthngcal sativerosytm of Caribbe jollyfishrfairly mp,in four“'Thopal视神经束)”nsd,cach of which hasy"bywic the jlyfisveois bsedw dark it ookcompared to the water and make their way rond it ncommo waters,nearby roots haveih onastOnly disanoad background.But inmurky watersv nearbyroois can blend into their sroudinand have lowconrast.Thesarchers wondered ifCaribbean box jellyfishou that owcontrast objets-which might at first secmdistant-were actually closc by.To find out,the team put 12 jellyfish into a round water tank.The tank was surroundedby low-contrast gray and white stripes(),which might appear to a jellyfish like roots inclear water.A camera filmed the animals for about seven minutes.At first,they seemed tosee the gray stripes as distant roots and swam away,ending up bumping the tank wall.Butthose collisions (seemed to lead the jellyfish to reconsider the stripes.Soon,thecreatures treated the gray stripes more like close roots in murky water-and avoided them.This suggests that the rhopalia alone can learn that seemingly distant,low-contrast objectsare in fact close enough to avoid.That,in turn,hints that these nerve centers are behindCaribbean box jellyfish learning."That's the coolest part of the paper,"says Ken Cheng,a biologist at MacquarieUniversity.Sydney,Australia."That gets us one step down into the wiring of how it works."For Gaelle Botton-Amiot,tracing learning to the rhopalia raises new questions."They havefour of these things in their bodies.So how does that work?"asks this neurobiologist.If ajellyfish loses one of its rhopalia,does it forget everything those eyes saw and the neurons hadlearned?Or do the other rhopalia remember it?Jellyfish are able to avoid obstacles becauseA.they use brain cells to process information gatheredB.they rely on different levels of visual signal inputC.they have unique organs to measure the distanceD.they are driven by excellent survival instinctWhich of h followingorssthe ntheunderined1A.Unusual.B.Cloudy.C.Deep.D.Rapid.What can we infer from paragraphs 2 and 3?A.Jellyfish usually tend to be scared off by the gray color.B.Jellyfish tend to compare stripes with mangrove roots.C.Stimulation in orold nvironment backed the finding.D.Rhopalia are in control of the ellyfishmemorysytm英语试题（附版）第7贞（其2负）
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