43 According to the passage, what is the new trend in raising pigs?
(A)To raise pigs for a high yield of meat and a high yield of fat.
(B)To raise pigs for a low yield of meat and a high yield of fat.
(C)To raise pigs for a high yield of meat and a low yield of fat.
(D)To raise pigs for producing more piglets.

答案：登入後查看
統計： A(95), B(91), C(694), D(31), E(1) #610805

詳解 (共 2 筆)

#2150317
As the demand fornfa...
(共 346 字，隱藏中）
前往觀看
12
0
#3624131
To a great extent程度, we owe our current high standard of living to biological advances in food production.
Plant and animal breeders飼養員 have developed organisms that provide better sources of food than the original varieties不同品種.
Corn is a grass植物、草 that produces its seeds種子 on a cob玉米的穗轴.
The original corn plant had very small ears that were perhaps only three or four centimeters long. 
Through通過 selective breeding繁殖, varieties of corn with much larger ears and more seeds per cob plant have been adapted適合 to produce other kinds of corn, such as sweet corn and popcorn.

        Animal breeders also have had much success. 
The pig, chicken, and cow of today are much different animals from those available even 100 years ago. 
Chickens lay 産（蛋） more eggs, dairy cows give more milk, and beef cattle肉牛 grow faster. 
All of these improvements raise our standard of living. 
One interesting example is the change in the kind of hogs（供食用的）豬 that are raised. At one time同時, farmers wanted pigs that were fatty富含脂肪. 
The fat could be made into lard豬油, soap, and various other products. 
As the demand要求 for fat products of pigs declined減少, animal breeders developed pigs that gave a high yield of meat and relatively相對地 little fat. 
Today, plant and animal breeders can produce plants and animals almost to specifications規範.
3
0