直线用英语说是 "line". 来源是拉丁语 "linum"，意思是 "线".

例句：

The pencil drew a straight line on the paper. (铅笔在纸上画了一条直线。)

The teacher drew a line on the blackboard to show the students the concept of a line. (老师在黑板上画了一条线来向学生展示直线的概念。)

The border between the two countries is a straight line on the map. (两国的边界在地图上是一条直线。)