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问题 解答题

周长相等的两个长方形它们的长和宽也一定相等．______．

答案

当周长为12厘米时，一条长与宽的和就是6厘米，

则这个长方形的长、宽可以为4厘米、2厘米，也可以为5厘米、1厘米．

所以长和宽不一定相等．

故选：B．

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 the 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 Knickerbocker 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 modern 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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单项选择题

异步电动机是一种（）的设备.

A、高功率因数

B、低功率因数

C、功率因数是1

D、功率因数是0
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