何为交流发动机的输出特性、空载特性、外特性？
参考答案：
输出特性：发电机输出电压一定时，输出电流与发动机转速之间的函数关系。
空载特性：发电机空载运行时，发电机端电压与转速之间的函数关系。
外特性：发电机转速一定时，发电机端电压与输出电流之间的函数关系。
交流发电机的输出特性又称负载特性或输出电流特性。它是指发电机向负载供电时，保持发电机输出电压恒定，即Ut=C时，输出电流I与转速n之间的关系，I=f（n）的函数关系。
空载特性：发电机空载时（即负载电流I=0），发电机的端电压U和转速n之间的函数关系。
外特性：发电机转速一定时，发电机的端电压U与输出电流之间的关系，即n为一定值时，U=f（I）的函数关系。
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| In our classroom you can see there is a l of a park on the back wall. You can also see many children _ 2 the park. There is a river in it. Near the river there are not 3 , but there are many trees. Many 4 _ are singing in them. Near the trees there are some old men. They are sitting at a table. They are 5 tea and talking. There are two girls over there. They 6 new blouses. They are talking near the river. We can also see two boats in the picture. One is _ 7 but in 8 boat there are many children. Are there any young men in the _ 9 ? Let me see, there are some. They are swimming now. What are the boys doing? They are 10 _ there. | ||||
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