It's important to know when the letters have a bar on top like (a), that means you have to draw a segment, as the image below shows.
When the letters have an arrow on top and this arrow as no ending points, that means you have to draw a line which must be infinite.
At last, when the letters have an arrow with one endpoint, then you have to draw a ray that has one ending point and the other extreme is infinite.
There you have them, all the corresponding representations.
