细菌与绿色植物的根本区别是（   ）

A．有无成形的细胞核

B．有无细胞壁

C．有无细胞膜

D．有无细胞质

The time I had been looking forward to ________ at last and I saw my favourite star.[ ]

A. coming  

B. having coming

C. came  

D. come