TOEFL Listening: ETS-TOEFL听力机经 - YF75P3139K1J1P03P$

What does the professor say about X-rays, radio waves, and microwaves? A. They are all different forms of electromagnetic radiation. B. They all have important uses in modern technology. C. In large amounts, all may be dangerous to human Health. D. They can all be transformed into visible light.