【问】 He described it as’a very agreeable situation located within two small hills in the midst ofwhich flowed a great river.’(New Concept English，Book 3，L.17)

为什么定语从句in the midst of which flowed a great river中的主语和谓语要倒装?

【答】 作者把从句的主语a great river放在句尾，是为了使它处于信息焦点的位置，使其传递新信息。见end-focus和existential sentenses in Chinese and English。