与口腔癌发生相关的因素除外
A．吸烟B．长期不良机械刺激C．刷牙D．饮酒E．嚼槟榔
参考答案：C
碳元素对钢轨的性能影响很大，随着含碳量的增加，强度、硬度上升，塑性下降。
— Do you want a go?
— _______ [ ]
A. Maybe. What time?
B. See you later.
C. Don't worry!
D. It doesn't matter.
