Passage 9
In the past oysters were raised in much the same way as dirt farmers raised tomatoes by transplanting them. First, First, farmers selected the oyster bed, cleared the bottom of old shells and other debris, 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 cells 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 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 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 best a 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 little about the predators that attack and eat 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 resist to diseases, grew faster and larger, and flourished in water of different salinity and temperatures. In addition the cultivated oysters tasted better!
1. The best title for the passage would be .
［A］ the Threatened Extinction of Marine Life
［B］ the Cultivation of Oysters
［C］ the Discoveries Made by Marine Biologists
［D］ the Varieties of Wild Oysters
2. When did scientists discover that oysters were in danger?
［A］ In the early part of the nineteenth century.
［B］ At the beginning of this century.
［C］ In the 1940's
［D］ Just recently
3. The word that best describes the efforts of the marine biologists working with oysters is.
［A］ persistent
［B］ intermittent
［C］ traditional
［D］ fruitless
4. Which of the following best describes the organization of the passage?
［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.
2.5. 阐述型阅读理解练习 Passage 9
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