首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
In the past oysters were raised in much the same way as dirt fanners raised tomatoes—by transplanting them. First, farmers selec
In the past oysters were raised in much the same way as dirt fanners raised tomatoes—by transplanting them. First, farmers selec
admin
2013-01-20
44
问题
In the past oysters were raised in much the same way as dirt fanners raised tomatoes—by transplanting them. First, farmers selected the oyster bed, cleared the bottom of old shells and other remains, 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(贝卵). 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 delicious 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 best a luxury food. So they set up well-quipped 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 attacked and ate baby oysters by the millions. They failed, but they doggedly (努力) 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 lay eggs 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(盐分) and temperatures. In addition, the cultivated oysters tasted better!
At what stage of oysters did farmers begin to speed up their growth and fatten them up in the past?
选项
A、Shell.
B、Egg.
C、Larvae.
D、Spat
答案
D
解析
本题考查分析理解能力。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.
转载请注明原文地址:https://kaotiyun.com/show/f82O777K
0
考博英语
相关试题推荐
Childrenwhostayawayfromschooldo______fordifferentreasons.
Generally,acomputerisanydevicethatcanperformnumericalcalculations.Currently,【1】,thetermusuallyrefers【2】anelectr
IntheUnitedStatesandinmanyothercountriesaroundtheworld,therearefourmainwaysforpeopletobe【1】aboutdevelopment
Ifitwereonlynecessarytodecidewhethertoteachelementarysciencetoeverycneonamassbasisortofindthegiftedfewa
AlltherecentnewsonAIDSisbad.ThedeathofRockHudson【1】publicconcern-aboutthe【2】almosttothepointofpanic.Nowgen
Therearethreeseparatesourcesofhazard【1】totheuseofnuclearreactiontosupplyuswithenergy.Firstly,theradioactivem
I_______withthanksthehelpofmycolleaguesinthepreparationofthisnewcolumn.
Ifthereisonethingscientistshavetohear,itisthatthegameisover.Raisedonthebeliefofanendlessvoyageofdiscove
FirsttherewasaWashingtonPostarticlepublishedshortlyaftertheelectionsonthepresumptivenewHousespeaker,"MutedTon
Zoosareamongmankind’soldestinstitutions,datingbackatleast4500years,andprobablymore.Acrosstheworldtheyhavebr
随机试题
规定输入的字符串中只包含字母和*号。请编写函数fun,其功能是:除了字符串前导的*号之外,将串中其他*号全部删除。在编写函数时,不得使用c语言提供的字符串函数。例如,字符串中的内容为“****A*BC*DEF*G*******”,删除后,字符串中
巴金《怀念萧珊》的内容不包括()
下列误差中,全站仪可以通过盘左盘右取均值的方法消除的是()。
特种作业人员上岗前,必须进行专门的安全技术和操作技能的培训和考核,并经培训考核合格,取得()后方可上岗。
建设项目进度计划的跟踪检查与调整主要包括()。
为保障旅游业健康发展,国务院建立健全旅游综合协调机制,对旅游业发展进行综合协调。()
给定资料1.党的十九大报告提出的实施乡村振兴战略,正在温暖着各个村寨。乡亲们盼着乡村振兴,盼着农业强起来,生活富起来,农村美起来。基层干部反映,乡村振兴,急缺的就是资本。资本下乡,就是撬动乡村振兴的活水,是乡亲们的甘霖。随着我国“四化同步”
行为经济学认为,互惠行为是一种条件合作行为,是对善意和助人的行为进行回报。互惠行为通过实施报答的形式而使对方获得利益,这种报答往往通过降低或损害自我利益而实现。根据上述定义,下列属于互惠行为的是()。
Ittakesawholegalaxyofthingstomakeyouhappy.Happinessisastateyoufeelwhenyouhavenoproblems,worries,doubtsor
数字签名是(1),数字摘要(也称为数字指纹)是指(2)。
最新回复
(
0
)