There are seven kinds of complement clause, which can fill the object or subject (or, sometimes, a post-object) slot in a main clause. All Secondary and Primary-B verbs take complement clauses—but each one allows only some of the full range of complement clause possibilities. Which complement clauses a given verb may accept is determined by the meaning of the verb and the meanings of the complement clause constructions.

We outline the meanings of the different kinds of complement clause. Then deal with Secondary and Primary-B types, one at a time, looking at the overall meaning of each type and the specific meanings of individual verbs within the type, thus providing a semantic explanation for the complement clauses that occur.

We can recapitulate here the kinds of complement clause:

(i) THAT. The initial that may often be omitted when it immediately follows the main clause predicate.

(ii) WH-. This is introduced by whether/if, or by any other wh- word, e.g. who, what, where, when, how, why; this wh- introducer may not be omitted.

(iii) ING. The complement clause subject, if included, may in some circumstances be marked by ’s.

(iv) Modal (FOR) TO. If the complement clause subject is omitted, then for is also dropped. For may (with some verbs) or must (with others) be omitted when the complement clause subject is retained, and this then becomes surface structure object of the main verb.

(v) Judgement TO. Cannot undergo any NP omission. Complement clause predicate most often begins with be.

(vi) WH- TO. Similar to a Modal (FOR) TO construction where the complement clause subject is omitted under coreferentiality with main clause subject or object, and the complement clause is introduced by whether (not if) or by any other wh- word except why.

(vii) FROM ING. An ING clause with the subject (which is also surface object of the main clause) followed by from, the from being optionally omissible after one set of main verbs.

THAT and WH- complements have the full structure of a clause—they involve tense inflection, and may include a Modal. The other five kinds of complement clause cannot include either tense or a Modal. A subject must be stated for THAT, WH-, Judgement TO and FROM ING clauses, but can be omitted from ING and Modal (FOR) TO complements, and must be omitted from WH- TO clauses.

Some verbs that take an ING or Modal (FOR) TO complement must omit the complement clause subject (e.g. begin); others can optionally omit it (e.g. like); a further set must retain it (e.g. see, allow). A complement clause in object function, with no stated subject, is taken to have underlying subject coreferential with main clause subject; if the complement clause is in subject function, its underlying subject is taken to be coreferential with main clause object. Thus, Mary didn’t know where to put the box, and Where to put the box perplexed Mary.

A THAT, WH- or Modal (FOR) TO (but, generally, not an ING) complement clause in subject function may be extraposed to the end of the main clause, provided there is not also a complement clause in object or other postpredicate position.

It is important to repeat here one of the most important rules of English grammar: a preposition must be omitted before complementisers that, for and to. (It may optionally be omitted before a wh- word introducing a complement clause.)

The theoretical stance of this study involves investigating how semantic categories are mapped onto syntactic categories. The mapping is generally many-to-one. Thus, a number of semantic types are associated with each grammatical word class. A number of semantic roles correspond to each syntactic relation, e.g. Perceiver (with ATTENTION verbs), Speaker (with SPEACKING verbs), Experiencer (with LIKING verbs), Agent (with AFFECT verbs) all relate to the A (transitive subject) syntactic relation.

In a similar way, semantically diverse expressions may be mapped onto the same syntactic construction. Compare They began eating the chicken with They discussed eating the chicken; these are syntactically identical, with main verbs began and discussed, and complement clause eating the chicken. But They began eating the chicken describes an activity of ‘eating’, with begin being a Secondary verb that provides aspectual-type modification (and would in some languages be realized through a derivational affix to ‘eat’). In contrast, They discussed eating the chicken describes a discussion, and the topic of the discussion is eating the chicken.

The seven kinds of complement clause cover a wide semantic range. Consider:

. all BEGINNING verbs take ING complements, most also take a reduced Modal (FOR) TO;

. all WANTING verbs take Modal (FOR) TO complement, most also take THAT;

. all THINKING verbs take THAT or WH- complements, most also take Judgement TO, some ING, and a few Modal (FOR) TO;

. all LIKING verbs take ING, most also THAT, and some Modal (FOR) TO.

A given kind of complement clause may be applicable to all members of a certain type (because of the meaning of the type, and of the complement construction), but to just some members of another type (depending on the specific meanings of certain verbs within that type).

There are many examples of a single syntactic construction being used to code a variety of diverse semantic configurations.