1A 有叶绿体，能进行光合作用···························P

1  b 无叶绿体，不能进行光合作用··························2

2 a 无脊椎骨··································Q

2 b 有脊椎骨··································3

3 a 体温恒定，外被羽毛····························R

3 b 体温不恒定，体表裸露···························S

请选择上述五种生物中的四种填在后面四个空格：PQRS

实验一：先取3条大小不同的蚯蚓，放在一张湿纸上，然后用树叶、铅笔、红领巾分别在它们前面晃动，结果发现它们毫无反应。

实验二：找来几根葱、几块黄瓜和几块萝卜，并排放在蚯蚓前，几分钟后它们都钻到葱下面去了。

实验三：用泥巴、砖头砌了间小屋，把蚯蚓放在屋门口，结果发现它们很快朝屋里阴暗处爬去。