上行文一般有（）、多级行文、越级行文三种方式。
参考答案：逐级行文
---Doesn’t your father often go to work by bus ?
---____________. But ____________ he goes to work on foot.
A．No, he doesn’t . sometime
B．Yes , he does . sometimes
C．Yes, he does. some time
D．No, he doesn’t. sometimes
如果运费为每吨25美元，“运费”栏应填（）。
A．0.25%
B．502/25/2
C．25
D．可以不填
