铁路货物运输种类分哪几种？
参考答案：
分为整车、零担、集装箱三种。
His wife is in bad condition now and he has to_____ a smiling face though heavy-hearted in the company.[ ]
A. give
B. offer
C. prefer
D. present
下列哪项不是异体骨移植的主要用途是：（）
A．骨折治疗
B．充填大块骨缺损
C．骨肿瘤植骨
D．人工关节翻修术时充填骨缺损
