Summary

The traditional distinction between clause and sentence is important. A main clause combines with one or more subordinate clauses to form a sentence. Where different clauses occur in sentences can be described, as can where phrases occur inside clauses. Where sentences occur in texts cannot be described except very loosely. Sentences can be regarded as a low-level unit of discourse. Main clauses allow a very wide range of syntactic constructions and all the distinctions of aspect, tense and mood. In contrast, subordinate clauses allow a smaller range of syntactic constructions and fewer distinctions of aspect, tense and mood. There is a hierarchy of subordinate clauses. Complement clauses are least subordinate, relative and adverbial clauses are most subordinate. What were traditionally regarded as infinitive and gerund phrases are now treated as clauses on the ground that they express propositions and, like finite clauses, consist of a verb plus complements and adjuncts.