单项选择题
A．hydrogen, carbon, nitrogen, and oxygen atoms B．water vapor, ammonia, carbon dioxide, methane and hydrogen C．biomolecules and water D．evolutionary molecules
A．atoms and molecules B．chemicals C．plants, fish, dinosaurs and human beings D．the primitive soup
A．dissolve some new chemicals B．find out what may have happened on the Earth 4 billion years ago C．simulate bolts of lightning on the ancient Earth D．analyze a liquid