This paper analyzes the diachronic change of complement form from the that-clause into the to- infinitive clause, which is headed by a deontic predicative adjective. The rise of to-infinitive clauses and the decline of that-clauses from ME seemed to be caused by analogy and assimilation between verbal and adjectival mandative constructions. The analogical change was triggered by language internal factors such as the loss of inflections, word order reanalysis and the development of control construction as well as the principle of event integration and clause union, complexity principle and accessibility theory. In the deontic adjectival complement clause, the toinfinitive clause has been keeping roughly 3:1 to the that-clause from ModE up to PDE. In addition, adjectival complements with to-infinitives have shown less abrupt and more constrained than verbal complements with to-infinitives. Such developmental process is related to the constraint on the syntactic operation that substitutes to-infinitive clauses for that-clauses. In fact, the that-clause could be changed into the to-infinitive clause only if the thatclause functions as a logical subject in the deontic adjectival complement clause. Futhermore, deontic adjectives can't be merged with an animate subject since predicative adjectives of this type don't connote subject-oriented activity.

In an effort to pave the way to understanding the syntax of the Participial Perception Verb Complements(PPVCs) in English, this paper examines various syntactic phenomena of PPVSs in light of generative grammar. By making three proposals on syntactic grounds, the parer resolves problems and answers questions surrounding the constituency, category and internal structure of PPVCs and case checking of the overt subject DP in the position right behind the perception verb. The advanced proposals are as follows: (a) PPVCs are single constituents with both nominal and clausal properties; (b) PPVCs are categorically TPs dominated by DPs in Davies and Dubinsky`s (1999) sense; (c) along the minimalist lines suggested in Chomsky (2000, 2001), the overt subject DP of PPVCs has its [-interpretable] case feature checked against the matrix perception verb as in the typical ECM construction.