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
61
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://www.kaotiyun.com/show/f82O777K
0
考博英语
相关试题推荐
Asmainstreamchipproductiontechnologyshiftsfromonegenerationtothenexteverythreetofiveyears,plantswithnewtechn
IntheUnitedStatesandinmanyothercountriesaroundtheworld,therearefourmainwaysforpeopletobe【1】aboutdevelopment
IntheUnitedStatesandinmanyothercountriesaroundtheworld,therearefourmainwaysforpeopletobe【1】aboutdevelopment
Ifitwereonlynecessarytodecidewhethertoteachelementarysciencetoeverycneonamassbasisortofindthegiftedfewa
AlltherecentnewsonAIDSisbad.ThedeathofRockHudson【1】publicconcern-aboutthe【2】almosttothepointofpanic.Nowgen
(66)Astateuniversitypresidentwasarrestedtodayandchargedwithimpersonateapoliceofficerbecame,theauthoritiessay,
Forgatheringdataaboutindividualsorgroupsatdifferentdevelopmentallevels,researcherscanusetworelatedresearchdesig
_____isthequestionofusingexistingresourcestoproduceoriginalandbeneficialsolutions,ideasorproducts.
Heraisedhiseyebrowsandstuckhisheadforwardand_____itinasinglenod,agestureboy,usedthenfor0.K.whentheywerep
Mariowasawardedthemedalfordisplayingprofessional______ofthehighestorderintherescueattemptstwoweeksago.
随机试题
设向量α1=(1,0,-1)T,α2=(0,1,1)T,α3=(-1,1,1)T,β=(2,3,0)T,则β由α1,α2,α3线性表出的表达式为_______.
A.计量资料B.计数资料C.等级资料D.间断性资料E.二分资料测量性别等指标所得的资料是
直径为38mm的平砂土样品,进行常规三轴试验,围压恒定为48.7kPa,最大竖向加载杆的轴向力为75.2N,那么该样品的内摩擦角为:
地面水环境影响预测中,污染源的简化包括()。
工程档案管理的工作流程属于建设项目信息管理任务中()方面环节的工作。
“教育对人的肉体和精神都要关心,但主要关心的应当是灵魂,教育应当建立在精神本质占优势的基础上”,这一观点是()教育目的论。
刘某为某县级市印刷厂工人,他向该市纪检委举报了该市人大副主任郝某收受钱物的行为,三个月后见市纪检委未采取任何措施,又向检察院报案。经查,郝某没有收受钱物的行为。那么刘某的行为属于下列哪种情形()
《中苏友好同盟约》(南京大学2013年中国近现代史真题)
数据库设计的标准结构为三级模式、二级映射,该结构的主要作用是()。
某市场调研公司对品牌商品销售情况进行调查后,得到下图(a)所示的销量统计数据。将图(a)所示的销售量按产品类别分类汇总,得到如图(b)所示的汇总结果。在进行分类汇总前,应先对图(a)的数据记录按(2)字段进行排序;选择“数据/分类汇总”命令,在弹出的“
最新回复
(
0
)