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
23
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
AnOhioStateUniversitystudyhaslinkedbehaviorinyoungchildren【1】thetypeofjobtheirmotherhas.Motherswithcomplexoc
Ifitwereonlynecessarytodecidewhethertoteachelementarysciencetoeverycneonamassbasisortofindthegiftedfewa
Ifitwereonlynecessarytodecidewhethertoteachelementarysciencetoeverycneonamassbasisortofindthegiftedfewa
AlltherecentnewsonAIDSisbad.ThedeathofRockHudson【1】publicconcern-aboutthe【2】almosttothepointofpanic.Nowgen
Therearethreeseparatesourcesofhazard【1】totheuseofnuclearreactiontosupplyuswithenergy.Firstly,theradioactivem
Therearethreeseparatesourcesofhazard【1】totheuseofnuclearreactiontosupplyuswithenergy.Firstly,theradioactivem
Itisimpossiblethatthebrain,______,willbereplacedbycomputer
TheoldestadulthumanskullyetfoundbelongstothelowestgradeofHomoerectus,andtotheAustraloidline.ItisknownasP
TheeventsofSept.11haveratchetedupsecurityatAmericanairportstothehighestlevelever,accordingtoaspokesmanforT
Experimentingwithhouseholdobjectscanoftengetyoungpeopleintrouble,butforoneintelligent,inquisitiveboy,itcreated
随机试题
患者,女,40岁。体形肥胖,近半年来右上腹部隐痛,疼痛向肩背部放射,伴有恶心、呕吐,胃镜检查报告轻度胃炎。为患者解痉止痛时禁用
下列哪一项不是消渴的典型症状
用平车运送患者时,做法不正确的是
规划决策民主化是规划决策科学化的重要前提,推进公众参与制度的做法不包括()。
某种围岩在采用分部分块开挖时,需先在顶拱处开挖导洞,然后进行顶拱扩大开防,并及时进行支护,那么这种围岩属于()级岩类.
下列有关2014年亚太经合组织会议的表述,错误的是()。
进程所请求的一次打印输出结束后,将使进程状态从
Iwillcomeearly,______busyImightbe.
A、Copythearticleaboutscorpions.B、Havelunchwithhim.C、Buybooksaboutscorpions.D、GotoCanadawithhim.A对话末尾,男子说他想要一份这
A、Sheholdsthatonedollarforeachyearoftheageisfarfromenough.B、Shebelievesthatchildrenshouldbegivenmorethan
最新回复
(
0
)