- Have you bought that digital camera?

- No, I can’t afford it. The price is a bit too ________, I think.[ ]

A. low

B. high

C. cheap

D. expensive

生物多样性的物质基础根本是（）

A.蛋白质的多样性

B.DNA分子的多样性

C.核酸的多样性

D.核苷酸的多样性