In the oysters were raised in much the same way as dirt farmers raised tomatoes- by transplanti" />

奶昔直播官方版-奶昔直播直播视频在线观看免费版下载-奶昔直播安卓版本免费安装

  首頁 課程  書店 學(xué)校  題庫 論壇  網(wǎng)校  地方分站: 北京 | 上海 | 鄭州 | 天津 | 山東
報(bào)名咨詢熱線:010-51268840、51268841
 新托�?荚嚲W(wǎng)
考試資訊  報(bào)考指南  備考寶典  考場經(jīng)驗(yàn)  閱讀輔導(dǎo)  真題  模擬題  學(xué)友圈  網(wǎng)校課程 熱門下載
   聽力 | 寫作 | 閱讀 | 口試   北京新航道托福精品課程   環(huán)球雅思托福熱門課程   新東方托福網(wǎng)絡(luò)課程      托�?荚嚧鹨蓞^(qū)

高效備考新托福寫作之托福范文34

作者:   發(fā)布時(shí)間:2011-09-06  來源:育路教育網(wǎng)
  • 文章正文
  • 網(wǎng)校課程
  • 資料下載
  • 熱門話題
  • 論壇
無標(biāo)題文檔
  Raising Oysters
  In the 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, 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 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 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 resistant to diseases, grew faster and larger, and flourished in water of different salinities and temperatures. In addition, the cultivated oysters tasted better!
熱門資料下載:
新托福考試論壇熱貼:
【責(zé)任編輯:育路編輯  糾錯(cuò)
[an error occurred while processing this directive]
新托福培訓(xùn)咨詢電話:010-51294614
報(bào)考直通車
 
·新托福最近考試時(shí)間:2011年9月11日。
·考試內(nèi)容:閱讀、 聽力、口語、寫作。
課程推薦
                   
[an error occurred while processing this directive]
 新托�?荚囕o導(dǎo)