TOEFL Listening: ETS-TOEFL听力机经 - N71O8HHN88YW583AP$

What is the main purpose of the lecture? A. To discuss the advantages of heating substances in microwave ovens B. To discuss recent research that may lead to improved microwave ovens C. To point out problems in the use of superheating to produce medicines D. To prepare students for upcoming experiments in the laboratory