Exercise

　　Human beings have 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.

　　These expenses , however, usually involve the rent of a small office , expenses for stationary, and possibly , the salary of a secretary.

　　He must assume that you have lived in the tropics , have never seen a coat worn or put on, and that he is to tell you verbally how to do it.

　　要點分析和參考譯文

　　要點：此句為一個多層次的并列結構，“by” 以前的部分為句子的主體部分，由“and”連接的兩個并列的分句組成。第二個分句的主語和一部分謂語省略了以避免重復。In doing so可以理解為in the process of distinguished themselves from other animals.第二個分局的完整句子應為and in doing so （they have） ensured their survival.By 所引導的短語里ability帶了多個動詞不定式做修飾，這些不定式又存在著一個并列的結構，to observe and （to） understand與either……or引導的to adapt to……，to control and （to） adapt it……得并列，and連接。
　　參考譯文：人類已把自己和其他動物區別開了。人類具有觀察和了解周圍環境的能力，能適應環境，控制環境和根據自己的需要改造環境。人類就是這樣生存了下來。

　　要點：在謂語動詞involve 后面是由三個平行的名詞短語構成的賓語：he rent of a small office , expenses for stationary, the salary of a secretary.副詞however及possibly 為插入語。
　　參考譯文：然而，這些費用通常包括租賃一間小小的辦公室和辦公用品的支出，或許還要包括秘書的工資。

　　要點：本句中, that 引導的賓語從句共有三個，have never seen……，是一個省去了引導詞that及主語you的賓語從句；過去分詞worn or put on作賓語coat的補語。
　　參考譯文：他肯定以為，你一直居住在熱帶從來沒有見過穿在身上的外衣或怎樣穿外衣，故而他要告訴你如何穿外衣。