单项选择题

Scientists figured out that human bodies are basically made of ______.

A．hydrogen, carbon, nitrogen, and oxygen atoms
B．water vapor, ammonia, carbon dioxide, methane and hydrogen
C．biomolecules and water
D．evolutionary molecules

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热门试题

单项选择题

According to the writer, living things on Earth have included ______.

A．atoms and molecules
B．chemicals
C．plants, fish, dinosaurs and human beings
D．the primitive soup

单项选择题

At the end of the last paragraph, the word it refers to ______.

A．water
B．the liquid sample
C．a closed loop
D．an electric spark