单项选择题


Questions 25 and 26 are based on the following news. At the end of the news item, you will be given 10 seconds to answer the questions.
Now listen to the news.
Which opinion did the discovery prove

A.Modem birds are the closest living relatives of the two-legged dinosaurs.
B.Dinosaurs have medullary bone.
C.Medullary bone is only known in ovulating birds.
D.Medullary bone is a source of calcium for birds to make shells for their eggs.