Science A sound wave and the air molecules around your ear.
1 moves and shakes
2 vibrates and heats up
3 compresses, expands

It's to know your purpose before you read something because a purpose can:

How does thoreau defend his approach in the second paragraph of "economy" inwalden? -he uses the word "t" because he feels it sounds more interesting-he does not use first-person point of view because his is a fictional account-he uses first-person point of view to get his readers' attention-he uses the word "t" for the sake of sincerity and honesty.

What does moon shadow think about where the tang people live (text evidence)