— Why does the lake smell terrible?

— Because large quantities of water ________.[ ]

A. have polluted  

B. is being polluted

C. has been polluted  

D. have been polluted

据图示回答下列问题

(1)判断甲乙两图中属于原核细胞的是__________，判断的主要依据为_____________。

(2)甲乙两细胞结构的相似之处为都有__________由此看出原核细胞与真核细胞具有_________性。

(3)甲的遗传物质是____________，主要位于_____________中；乙的遗传物质是__________，主要位于______________中。

(4)常见的由甲种细胞组成的生物有_____由乙种细胞构成的生物有____________。(至少各写三种)