— Do you think we should accept that offer?

— Yes, we should, for we ___such bad luck up till now, and time __ out. [ ]

A. have had; is running        

B. had; is running

C. have; has been run          

D. have had; has been run

自牙颈部牙骨质，向牙冠方向散开，广泛存在于牙龈固有层，牵引牙龈与牙齿紧密结合

A．龈牙组
B．牙槽龈组
C．环形组
D．牙骨膜组
E．越隔组