TOEFL Listening: ETS-TOEFL听力机经 - R82YK311O139PWJ5P$

According to the professor, why is a fresco painted before the plaster dries? A. So that mistakes can be corrected easily B. So that the paint will sink into the plaster C. So that the colors of the paints can be blended better D. So that human forms will appear more lifelike