本句中，define…as意为“给……下定义”或“将……定义为”。That in general are soluble in ether… in water 是定语从句，修饰a group of substances; that with proteins and carbohydrates constitute the principal structural components of living cells也是定语从句，也修饰a group of substances。作为as的宾语，any of a group of substances, related and derived compounds, steroids and carotenoids三者是并列的。

 

 

         fats and oil 为主句主语， as frying fats or cooling oils的as短语做主语的补语， where引导的状语从句修饰谓语are used,此从句中有两个并列的不定式动词 to provide as 和to contribute.

 

        as shortenings 为目的的状语，主语they 指上文中的fats and oils, through 带出的介词短语（至句末）修饰谓语important 的方式状语。Lubrication 和ability为介词of 的并列宾语，构成的介词短语修饰a combination; To alter…other constituents 为不定式短语，作an ability 的定语； among other constituents 是介词短语，作定语，修饰interaction.