Cleft sentence

Cleft sentences are used for emphasis, and transform a short sentence into as longer, more emphatic form. There are two types of cleft sentences: subject and object cleft sentences.

Structure
Cleft sentences follow a few common structures:
 * IT + BE + NOUN + RELATIVE PRONOUN + VERB as in "It was you who stole my ring"
 * WHAT + NOUN + VERB(S) + BE as in "What you need is a haircut", or "What she should do is get a life"
 * THE + NOUN + DEFINING RELATIVE CLAUSE + BE as in "The pub (that/which) my friends like is over there", or "The bloke who/that spilt my drink is over there"

Relative clauses in cleft sentences
If a cleft sentence contains a relative clause (see above), the grammar of subject and object relative clauses also applies within the cleft sentence. In cleft sentences with object relative clauses, a relative pronoun is necessary; however, in cleft sentences wih a subject relative clause, a relative pronoun is optional. Compare the following examples: