输入微生物、人体组织、生物制品、血液及其制品或种畜、禽及其精液、胚胎、受精卵的，应当在入境前15天报检。( )

The gold loop discovered in the ancient tomb _____ to be _____in studying the history of the

Jin Dynasty. [ ]

A. was turned out; valuable                    

B. proved; of great value  

C. was proved; of great valuable                

D. proved; much valuable