题目内容：

Animals that could not adapt themselves to the environment perished and those that could survived
其中that could survived 中的 that 那么理解 为什么这么用
为什么 用 those又用that

优质解答

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.