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问题 单项选择题

一台三相同步发电机在对称负载下稳定运行，当电枢电流与空载电动势之间的夹角为-90°＜ψ＜0°时的电枢反应为()。

A．直轴助磁电枢反应

B．既有直轴去磁电枢反应，又有交轴电枢反应

C．既有直轴助磁电枢反应，又有交轴电枢反应

D．既有直轴电枢反应(去磁或助磁不确定)，又有交轴电枢反应

答案

参考答案：C

单项选择题

根据学习的定义，下列属于学习的现象是()

A．吃了酸的食物流唾液

B．望梅止渴

C．蜘蛛织网

D．孩子模仿电影中人物的行为
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单项选择题

Children are a relatively modem invention. Until a few hundred years ago they look like adult, wearing grown-up clothes and grown-up expressions, performing grown-up tasks. Children did not exist because the family as we know it had not evolved.
Children today not only exist; they have taken over in no place more than in America, and at no time more than now. It is always Kids Country here. Our civilization is child-centered, child-obsessed. A kid’s body is our physical ideal. In Kids Country we do not permit middle-aged. Thirty is promoted over 50, but 30 knows that soon his time to be overtaken will come.
We are the first society in which parents expect to learn from their children. Such a topsy-turvy situation has come to abort at least in part because, unlike the rest of the world, ours is an immigrant society, and for immigrants the only hope is in the kids. In the Old Country, that is, Europe, hope was in the father, and how much wealth he could accumulate and pass along to his children. In the growth pattern of America and its ever- expanding frontier, the young man was ever advised to GO WEST; the father was ever inheriting from his son. Kids Country may be the inevitable result.
Kids Country is not at all bad. America is the greatest country in the world to grow up in because it is Kids Country. We not only wear kids clothes and eat kids food; we dream kids dreams and make them come tree. It was, after all, a boys’ game to go to the moon.
If in the old days children did not exist, it seems equally true today that adults, as a class, have begun to disappear, condemning all of us to remain boys and girls forever, jogging and doing push-ups against eternity.

The young man was advised to Go West to ______ .

A．find and accumulate more wealth
B．get more free land for the family
C．be the pioneers of the West
D．expand the country’s territory
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