图是某雄性动物细胞分裂的模式图，请据图分析回答：

（1）该细胞的分裂方式是____ ，细胞中含有____ 个核DNA分子，该动物体的细胞中染色体数目最多为____ 　条．

（2）若图中①上某位点有基因B，②上相应位点的基因是b，则发生这种变化的根本原因可能有____ 

（3）图示细胞分裂完成后形成的子细胞称为____ ，该细胞中的所有染色体构成了一个____ ．

在做“利用电火花打点计时器测定匀变速直线运动的加速度”的实验中，取下一段如图所示的纸带研究其运动情况．设O点为计数的起始点，每间隔4个计时点取一个计数点，则计数点A与起始点O之间的距离S₁为____ cm，打计数点A时物体的瞬时速度为____ m/s，物体的加速度为____ m/s²．

美国前总统布什说过：“法国曾经是美国在世界上的第一个朋友，现在仍是美国不可侵害的朋友之一。”句中所指的“第一个朋友”与下列哪一历史事件有关(   )

     Yesterday my sister and I went____(buy)something for her birthday．She didn't really know what____(get)but she seemed____(like)the idea of a pet，so we went to the nearest pet shop．She started ____(look)around at an the animals．The man in the shop advised her ____(choose)the rabbits，but when she saw some puppies(小狗) ____(play)in the box，she said she would like____(have)one of them．I didn't know if we had enough money____(buy)one and I hoped my mother would want us____(have)a dog in the house，but my sister promised____(look after)it well and we had enough money，so we bought a little brown dog.