Summary

Three major types of subordinate clause are recognized: complement clauses, relative clauses and adverbial clauses. Complement clauses modify either verbs or nouns, can function as subject or object in a clause and have as their complementiser that or zero. Relative clauses modify nouns and have as their complementiser a WH word or that or zero. Relative clauses differ further from complement clauses in that, without a WH complementiser, they lack a subject or object. This also applies to relative clauses introduced by that or zero. Adverbial clauses modify other clauses. Rules of thumb based largely on modification help to pick out the different types of clause.