被称为城市的肾的杭州湾湿地景观带,湿地内土地肥沃、潮湿,是野生动植物的天然场所,湿地内有几百种动物和植物。常见的有白鹭、螃蟹、蛇、芦苇、青蛙,有同学为它们编了一个检索表,请帮助他继续完成。
1 a 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