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.

康奈尔大学的研究者用胶原蛋白的耳细胞创造出了更自然的活的人工耳；荷兰研究者利用干细胞培养出的肉纤维，做出了第一个完全诞生于培养皿中的人造肉饼。这从一个侧面证明（   ）

①人类改造自然的活动要以自然物的客观性为前提

②意识活动有创造性，能依据自己意愿创造新物质

③人们可以利用对规律的认识，改造世界造福人类

④意识能动性是人们正确改造客观世界的可靠保证

圆周率π是一个无限不循环小数。我国三国时代的刘徽算出圆周率为3.141 6。南北朝时，祖冲之算出圆周率在3.141 592 6和3.141 592 7之间。当代，有人利用计算机把π的值算到了数千亿位数，但仍然没有穷尽，也不会穷尽。这说明人类对圆周长与直径之比的认识，始终是近似的。该例说明 (　　)