直流电动机的弱磁调速是恒转矩调速，转速只能从额定转速往上调节，而调压调速，功率调速，转速只能从额定转速往下调节。
参考答案：错
I let the meat cook too long, so it was ______ black. [ ]
A. burned
B. kept
C. prepared
D. tasted
新人点烛台点一半时，点火棒熄灭或不能继续点燃。您怎样说？
