Question

Animals that could not adapt themselves to the environment p

Answer 1

两个that引导的是定语从句,引导词分别是animals和those,两个引导词在从句中都是主语,句子构成是这样的：

Animals (that could not adapt themselves to the environment) perished and those (that could)survived.

第一个括号里是animals的定语,意思是：（那些不能适应环境的）动物；

第二个括号完整的应该是that could adapt themselves to the environment,是those（代指animals）的定语,意思是：（那些能适应环境的）动物；

整句话直译的话是“不能适应环境的物种遭到灭绝,能适应环境的得以存活.”

其实就是“物竞天择,适者生存”的意思.