In the past oysters were raised in much the same way as dirt farmers raised tomatoes-by transplanting them．First，farmers selecte

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问题 In the past oysters were raised in much the same way as dirt farmers raised tomatoes-by transplanting them．First，farmers selected the oyster bed，cleared the bottom of old shells and other debris，and then scattered clean shells about．Next they “planted”fertilized oyster eggs，which within two or three weeks hatched into larvae.The larvae drifted until they attached themselves to the clean shells on the bottom．There they remained and in time grew into baby oysters called seed or spat．The spat grew larger by drawing in seawater from which they derived microscopic particles of food．Before long，farmers gathered the baby oysters，transplanted them in other waters to speed up their growth，and then transplanted them once more into another body of water to fatten them up。
Until recently the supply of wild oysters and those crudely farmed were more than enough to satisfy people’s needs．But today the delectable seafood is no longer available in abundance．The problem has become so serious that some oyster beds have vanished entirely。
Fortunately，as far back as the early 1900’s marine biologists realized that if new measures were not taken，oysters would become extinct or at least luxury food．So they set up well equipped hatcheries and went to work．But they did not have the proper equipment or the skill to handle the eggs．They did not know when，what，and how to feed the larvae．And they knew 1ittle about the predators that attacked and ate baby oysters by the millions．They failed，but they doggedly kept at it．Finally，in the 1940’s a significant breakthrough was made．
The marine biologists discovered that by raising the temperature of the water，they could induce oysters to spawn not only in the summer but also in the fall，winter，and spring。Later they developed a technique for feeding the larvae and rearing them to spat．Going still further，they succeeded in breeding new strains that were resistant to diseases，grew faster and larger，and flourished in water of different salinities and temperatures．In addition，the cultivated oysters tasted better!
Which of the following best describes the organization of the passage?

选项 A、Step by step description of the evolution of marine biology．
B、Discussion of chronological events concerning oyster production．
C、Random presentation of facts about oysters．
D、Description of oyster production at different geographic locations．

答案B

解析判断推理题。文章每段段首皆有表示时间的词或短语，由此可见文本是按照时间顺序记述关于生产牡蛎的事情，选项A是说一步一步描写海洋生物的进化，选项C是说随意地陈述关于牡蛎的事实，选项D是说描述不同地点的牡蛎。都不符合题意，故选择B。

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大学英语四级

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In the past oysters were raised in much the same way as dirt farmers raised tomatoes-by transplanting them．First，farmers selecte

大学英语四级

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