直流电机（）时会产生严重的火花。
A.电枢电流大
B.励磁电流大
C.输出转矩小
D.输出功率小
参考答案：A
---- Why are you in such a hurry?
---- My girlfriend ____ for Shanghai. I’m going to the airport to see her off.
A．is leaving
B．has left
C．was leaving
D．left
分泌型IgA主要产生部位
A．淋巴结B．脾脏C．骨髓D．外周血E．黏膜相关淋巴组织
