line polar or a curve

例句：

1. 1. The artist carefully drew a line on the canvas.
   艺术家在画布上小心地画了一条线。
2. 2. She used a ruler to draw a straight line across the paper.
   她用直尺在纸上画了一条直线。
3. 3. The teacher asked the students to draw lines on the blackboard.
   老师要求学生们在黑板上画线。