知识产权管理主要内容包括（）。A、知识产权的开发管理 B、知识产权的经营使用管理 C、知

道德评价的标准（）。

A.美与丑

B.虚与实

C.公与私

D.善与恶

E.人与物

简述电控燃油喷射系统的基本工作原理？

哪种力的量子化还没完全实现（）

A、弱相互作用

B、引力

C、强相互作用

D、电磁力

经调查，某生态系统中Y、X、Z分别为第一、第二和第三营养级，每个营养级不同物种的个体数量如图甲所示（图中每一柱条代表一个物种）。一段时间后个体数量发生变化，结果如图乙所示。下列叙述正确的是（）

A．X营养级的生物被捕食的压力明显增加

B．Z营养级生物个体数量的增加是由捕食对象专一引起的

C．Y营养级生物个体数量的变化是由于捕食者对捕食对象有选择的结果

D．X营养级的生物之间存在明显的竞争关系，且其中某种生物处于竞争劣势

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 tone of the passage is ______.

A. persuasive



B. informative
C. biased



D. argumentative