例251　Human beings have long distinguished themselves from other animals, and in doing so ensured their survival, by the ability to observe and understand their environment and then either to adapt to that environment or to control and adapt it to their own needs.

【结构分析】这句话是由两个并列句构成，第一个并列句子的主干是Human beings have long distinguished themselves from other animals，第二个并列句的主干是ensured their survival，第二个并列句里面有介词短语by the ability，后面有三个不定式to do修饰前面的the ability，第一个不定式是to observe and understand their environment，第二个不定式是to adapt to that environment，第三个不定式是to control and adapt it to their own needs。

【亮点回放】此句话的亮点在于大并列里面套上小并列，主句并列套上三个不定式的小并列，三个不定式的小并列修饰第二个并列句的宾语，这么多并列很有气势。

【核心词汇】

distinguish from　区分

ensure their survival　确保生存

adapt to　适应

their own needs　他们的自己的需求

【参考译文】人类长期以来把自己和别的动物区分开来，而且为了实现这一点确保自己的生存，他们具备观察和了解周围环境的能力，然后要么适应环境，要么让环境适应自己的需求。