—Has he been in Jinan since 2001?

—Yes. He _____ here eight years ago.[ ]

A. come      

B. came          

C. is coming        

D. has come

视网膜中央动脉为______眶内段的分支，在眼球后______处从内下或下方进入______中央，再经视盘穿出分为______、______、______、______4支，走行于视网膜神经纤维层内，逐级分支达周边部。