How to draw a straight line with a straight pole?

There are two kinds of vertical and horizontal. 1: 90-degree stroke, but this kind of play is difficult, and generally only professionals can play it. 2. Wrist style, driving the ball with the wrist to make the ball spin. In addition, keep the shape of the racket, and it is difficult for the opponent to pull again after changing the line. This style of play has a high success rate, but it needs more practice.