COMP as a functional head

Motivation for assuming a COMP node:

I. Embedded clauses are commonly introduced by means of a certain element, known as the complementizer (e.g. that).

II. Verbs that take sentential complements:
(a) commonly select a particular kind of complement:

(i) verbs like ask take interrogative complements
(ii) verbs like think take declarative complements

(b) can place such specific requirements only on the heads of their complements, if we assume that the features of a phrase originate on its head.

III. We thus hypothesize the functional head COMP, which dominates the functional clause-type feature (or complementizers that realize this feature). This feature is referred to as [WH] and can have two values: [+WH] for interrogative (e.g. complementizer whether) and [-WH] for declarative (e.g. complementizer that).

Some properties of COMP
The structure of CP

Exercises on COMP as a functional head