whphrases

Whphrases are a class of syntactic constituents used to introduce interrogative and relative clauses in many languages. In English, they consist of a wh-word plus any necessary modifiers, including who, what, where, when, why, how, which, and whose, as well as longer forms such as how long or which book. Whphrases function as the interrogative operators that request specific information or identify a referent, and they can also introduce relative clauses, linking to an antecedent noun phrase in what is called a relative wh-phrase.

In questions, whphrases typically move to the clause-initial position, with English showing auxiliary inversion: What did you see? In relative clauses, a whphrase can introduce the clause but binds to a position inside: The book which you read. There are exceptions, such as languages without verb movement or with different agreement systems.

Whphrases can serve various syntactic roles: subject, object, complement, or adverbial modifier. They interact with negation, tense, and aspect. They can also be fronted or appear as part of longer phrasal forms such as how long or which of the books.

Cross-linguistic variation is typical. Some languages use wh-words that do not require movement (for example, Mandarin uses wh-words with fronted particles but without the same inversion as English), while others mark wh-constraints with case or agreement. In many languages, multiple wh-words exist; some languages distinguish direct from indirect questions.