EXCLAMATIONS :!: are sentences used to express the speaker's feeling or attitude. They express an extreme degree of some variable factor, but the variable may be left implicit. Thus, what a day! could refer to a very good/bad one.
The exclamative clause is a way of showing enthusiasm, but it's not the only one. According to Carter & McCarthy (2006), interrogative clauses can function as exclamations when they don't necessarily require any informative reply from the listener, but they invite the listener to agree on sth on which the speaker has strong feelings. The most characteristic form of such interrogatives is that of a yes/no question with a falling tone: It was a very good school, but was I lamentably bad at maths!
STRUCTURE: beginning the sentence with what or how without inversion of subject and operator. They're often shortened to a noun/adjectival phrase. In written form, they end with an exclamation mark: How funny!
Exclamatives resemble wh-questions in involving the initial placement of an exclamatory X-element, which may be subject, object, complement, and adverbial, but it can also act as a prepositional complement, with the preposition postponed: What a mess we're in! (ASV)
- How is more characteristic of formal style than exclamative what, which is different from the interrogative because it refers to degree and not identity and syncatically it occupies the determiner position and it can never be a pronoun. On the other hand, How differs from the interrogative in that it belongs exclusively to the adverb class, and it cannot be an adjective.
