阅读下面材料，在空白处填入适当的内容（1个单词）或括号内单词的正确形式。    

Chengdu has dozens of new millionaires, Asia’s biggest building, and fancy new hotels. But for tourists like me, pandas are its top（61）(attract).

So it was a great honour to be invited backstage at the not-for-profit Panda Base, where ticket money helps pay for research, I（62）（arrow）to get up close to these cute animals at the 600-acre centre. From tomorrow, I will be their UK ambassador. The title will be（63）(official) given to me at a ceremony in London.But my connection with pandas goes back （64）my days on a TV show in the mid-1980s,（65）I was the first Western TV reporter（66）(permit) to film a special unit caring for pandas rescued from starvation in the wild. My ambassadorial duties will include（67）(introduce) British visitors to the 120-plus pandas at Chengdu and others at a research in the misty mountains of Bifengxia.

On mu recent visit, I help a lively three-month-old twin that had been rejected by（68）(it) mother. The nursery team switches him every few（69）(day) with his sister so that while one is being bottle-fed,（70）other is with mum-she never suspects.

67（）

甲图表示某种哺乳动物细胞在正常培养时所测得的细胞中DNA含量与细胞数的变化。用某种化合物处理培养着的细胞，结果DNA含量与细胞数的变化如乙图所示，该化合物所起的作用是（）

A.促进细胞分裂

B.抑制DNA的复制

C.抑制纺锤体的形成

D.促进DNA的高度螺旋化