题目

最近医学界通过放射性14C标记的C60，发现有一种C60的羧酸衍生物在特定条件下可通过断裂DNA杀死细胞，从而抑制艾滋病（AIDS）。有关14C的叙述正确的是A．14C与C60中碳原子的化学性质不同B．14C与14N含的中子数相同C． 14C与C60是同素异形体D．14C与12C互为同位素 答案：DTurn on the television or open a magazine and you _____ advertisements showing happy families. [     ]A. will often see B. often see C. are often seeing D. have often seen