收入事故的分类？
参考答案：
运输收入事故的种类分为：
现金事故、票据事故和坏帐损失。
She had just finished her homework ____ her mother asked her to practice playing the piano yesterday.
A．when
B．while
C．after
D．since
一次安全事故死亡14人属于（）。
A．大事故
B．重大事故
C．伤亡事故
D．特大伤亡事故
