Spring in Nanjing is very short .It is warm and sunny .People (人们) like to go to the parks on sunny days . It is very hot in summer in Nanjing .People do not like to play balls in the afternoon .They like to go swimming in summer . In autumn , it is cool and sunny. Many people like to come to Nanjing in autumn .In winter , it is cold in Nanjing .Boys and girls like to make snowmen and go skating . They have great fun in winter .

我国境内已知的最早使用天然火的原始人类是（    ）

科学家通过对化石的长期研究发现，在不同的地层中生活的生物是不同的，是有规律可寻的．在越古老的地层中，成为化石的生物（　　）