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问题 单项选择题 A3型题

一牛场陆续发生以母牛流产、关节炎，公畜睾丸炎为主的疾病。母牛流产后常发生胎衣不下进一步的诊断方法是（）

A.取病料分离细菌进行鉴定

B.PCR检查

C.血常规检查

D.血液生化试验

E.胎衣检查

答案

参考答案：A

单项选择题

提取病原体中有效免疫原制成的抗原称

A．灭活疫苗

B．合成肽疫苗

C．结合疫苗

D．亚单位疫苗

E．重组抗原疫苗
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单项选择题

There has been much speculation about the origin of baseball. In 1907 a special commission decided that the modern game was invented by Abner Doubleday in 1839. One hundred years later the National Baseball Museum was opened to honor Doubleday. Historians, however, disagree about the origin of baseball. Some say that baseball comes from bat-and-ball games of ancient times. It is a matter of record that in the 1700s English boys played a game they called "baseball". Americans have played a kind of baseball since about 1800. At first tile American game had different rules and different names in various parts of the country — "town ball". "rounders", or "one old cat". Youngsters today still play some of these simplified forms of the game.
Baseball did not receive a standard set of rules until 1845, when Alexander Cartwright organized the Knicker-bocker Baseball Club of New York City. The rules Cartwright set up for his nine-player team were widely adopted by other clubs and formed the basis of modem baseball. The game was played on a "diamond" infield with the bases 90 feet apart. The first team to score 21 runs was declared the winner. By 1858 the National Association of Baseball Players was formed with 25 amateur teams. The Cincinnati Red Stockings began to pay players in 1869.

The passage implies that until 1869, baseball was played for all of the following reasons EXCEPT ______.

A. exercise



B. leisure
C. profit



D. socializing
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