以下的因素已确定为引起牙髓炎的病因，除了（）。
A.感染因素
B.物理刺激
C.遗传因素
D.创伤
E.化学刺激
参考答案：C
What is Alice's hobby? [ ]
A. She is a teacher.
B. She is listening to music.
C. She goes to work by car.
D. She likes fishing.
变压器中性点应与什么连接？
