未知题型 鲢腹部膨大，内脏萎缩；剖检腹腔有大量胞囊。胞囊内可见近似圆形、具2个极囊、无嗜碘泡的虫体。该病最可能的病原是（）

单项选择题 New Foods and the New World In the last 500 years, nothing about people - not their clothes, ideas, or languages- has changed as much as what they eat. The original chocolate drink was made from the seeds of the cocoa tree (可可树) by South American Indians. The Spanish introduced it to the rest of the world during the 1500's. And although it was very expensive, it quickly became fashionable. In London, shops where chocolate drinks were served became important meeting places. Some still exist today.The potato is also from the New World. Around 1600, the Spanish brought it from Peru to Europe, where it soon was widely grown. Ireland became so dependent on it that thousands of Irish people starved when the crop failed during the 'Potato Famine (饥荒)'of 1845-1846, and thousands more were forced to leave their homeland and move to America.There are many other foods that have traveled from South America to the Old World. But some others went in the opposite direction. Brazil is now the world's largest grower of coffee, and coffee is an important crop in Colombia and other South American countries. But it is native to Ethiopia, a country in Africa .it was first made into a drink by Arabs during the 1400's.According to an Arabic legend, coffee was discovered when a person named Kaldi noticed that his goats were attracted to the red berries on a coffee bush. He tried one and experienced the 'wide-awake' feeling that one third of the world's population now starts the day with. 第 31 题 According to the passage, which of the following has changed the most in the last 500 years?A．Food.B．Clothing.C．Ideology.D．Language.

未知题型 9月，病鱖在池边无目标游动。剖检可见肝脏偏白且有淤血点，肠内充满黄色粘液，脾、肾肿大。同池混养的草鱼无异常。诊断最适宜的取样的部位是（）