Witch materials did artists use for the decoration of their works

Anyone have a site they can give me so i can get some drawings tutorials?

Sarah and juan were running in the school track meet. the muscles in their arms and legs them run fast. other muscles that you cannot see were also at work. the most important muscles for this track meet were the muscles in their a) arms. b) eye. c) feet. d) heart.

According to the article in wiki answer, digital communication systems have more benefits than analog systems. they are faster and more flexible, and they offer better performance than analog communication