Which two sentences clearly show that the purpose of the passage is to instruct?

How to Draw To learn how to draw you need the right instruments. You can choose to learn with a pencil or a felt tip pen. The advantage of the pencil is that you can erase any mistakes. On the other hand, learning to draw with a pen helps build confidence. Whatever you chose, the learning process is the same. You need to use good quality paper. This is particularly important if you use a pen. Once you have your drawing tool and paper, you are ready to learn. The first step is to learn to draw basic shapes. Start with drawing lines of varying lengths without the help of any other tool. Try to keep the lines as straight as possible. This is particularly challenging because the joint of your wrist tends to move in an arc. Once you start drawing straight lines, keep practicing. In fact, practice it every day! please its take like a day to get my answer back
1. The advantage of the pencil is that you can erase any mistakes.
2.This is particularly important if you use a pen.
3.Start with drawing lines of varying lengths without the help of any other tool.
4.Try to keep the lines as straight as possible.

These are the two sentences that clearly show that the purpose of the passage is to instruct. In these two sentences, the author is giving commands. In the first one, he asks the reader to draw lines of varying lengths without the help of any tool. In the second one, he asks him to keep the lines as straight as possible. In both of these examples, the author's goal is to instruct the reader about the best way to begin drawing.