railway line 铁路线;

telephone line电话线;

product/assembly line 生产/装配线;

county/state line 县/州界;

transmission line 传输线;

main line 干线;

power line 电源线;

bottom line 概要/关键;

online 在线的;

line of business行业，营业范围;

straight line直线;

dotted line虚线