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
