An original work or a scientist's experiment is called a
tertiary source
secondary source
primary source

When coal has reached it hardest, darkest form, it is called select one: 0 a. sub-bituminous b. lignite c. bituminous d. antrhacite next page

(99 points) be serious! how do farts work? how do you fart without it stinking? serious answers only

Which of the following is a testable hypotheses?