当二次电压正常,二次电流显著降低,可能是因为()造成的。
A.电晕极断线;
B.电晕线肥大;
C.电缆击穿;
D.气流分布板孔眼被堵。
参考答案:B
—How did your students express their thanks to you on Teachers’ Day?
—A gift together with many flowers _______ sent to me .
A.was
B.am
C.have been
D.had been
铸造前坯料加热的目的是()
A.提高塑性,降低变形抗力
B.提高强度、硬度
C.提高塑性和韧性