同步发电机的（）随负载变化而变化的特性称为调节特性。
A.端电压
B.励磁电流
C.电磁转矩
D.电磁功率
参考答案：A
单句改错
1. To my delighted, I passed the examination.
2. Hearing the news, he feels very delighting.
3. It is delight for me to help those poor children.
4. They were delighted at that the conference had been called off.
The mail was _____ for two days because of the snow storm. [ ]
A. held out
B. held off
C. held up
D. held down
