Mixed properties and matching effects in English free relatives: A construction-based perspective

English free relative clauses display dual properties. In terms of internal syntax, they are sentential, but in terms of external syntax, they behave like nominal expressions. These mixed properties assign many complexities to the constructions. Another intriguing property related to the mixed properties concerns matching and mismatching effects among the categorial information of the free relative, that of the wh-phrase, and the putative gap in the relative. This paper reviews these properties with investigating their authentic uses through the corpus COCA (Corpus of Contemporary American English) and then offers a construction-based analysis. The resulting analysis offers a streamlined analysis of English free relatives, avoiding pitfalls that previous analyses often encounter.