When a man has made any activity, and accumulated experience has occurred several times to make a human has to learn and develop what skill and learning, until a familiar with what happened.
When human activity has already accumulated a lot of experience and many times humans have to learn and what they learn to develop a skills and proficiency with things.
When humans do any activities, and accumulated experience, come over and many times of human has caused learning and develop what is learned until the skills and expertise to สิ่งนั้นๆ.