TOEFL Listening: ETS-TOEFL听力机经 - D9N82139X15D35C0P$

Why was ultramarine highly valued as a pigment during the first half of the fifteenth century? A. It was a shade of blue that had not been seen before in Italy. B. It was commonly used to decorate expensive jewelry. C. It was suitable for use both in paintings and on frames. D. It was a rich color that maintained its intensity over time.