They are verbs that take complement clauses.
Originally Posted by fantastic
"In many languages, certain verbs—notably 'see', 'hear', 'know', 'believe', 'like', and often also 'tell' and 'want'—can take a clause, instead of an NP (noun phrase), as a core argument. This is called a complement clause."Note that,
Relative cluases are not complement clauses. Relative clauses modify a noun phrase, whereas complement clauses are arguments which are selected by a verb [VP complement clause], noun, or adjective
. In some languages, relative clauses have a gap--a missing NP argument--which is understood to refer to the NP that the relative clause modifies. For instance, in "the person that saw you," the subject of the clause "saw you" is missing, but is understood to be "the person" that the NP as a whole refers to. Complement clauses do not usually have such a gap. For instance, in "the fact that he saw you," the clause "he saw you" does not have any missing arguments.
What is a complement clause?