题目

--Who is the old man talking with your teacher?   ---I don’t know. I     him before. A. was never seeing   B. had never seen   C. never saw  D. wouldn’t see 答案：C在细胞有丝分裂过程中，核DNA分子不会                                           A．发生水解         B．发生突变         C．进行转录         D．进行复制