有这样一道考题:It’s reported that the city needs more landA.on which to build housesC.which to build housesB.on which building housesD.which to build houses on 此题答案为A,许多同学不明白此句是什么结构。简单地说,这是一个紧缩了的定语从句,这类结构可归纳为“介词+关系代词+不定式”形式。在正式文体中,当引导定语从句的关系代词用作介词的宾语时,有时可用“介词+关系代词+不定式”这样的结构来简化定语从句。如: There is such an examination: It’s reported that the city needs more landA.on which to build housesC.which to build housesB.on which houses housesD.which to build houses on The answer to this question is A, many students do not understand what the structure of this sentence is . Simply put, this is a condensed attributive clause, and this kind of structure can be summarized as “preposition + relational pronoun + infinitive” form. In formal genre, when the relative pronouns of the attributive clause are used as the object of prepositions, the prepositional clause can be used to simplify the attributive clause. Such as: