Word families and classes across registers
Comparing lexical words in use : Nouns and verbs are clearly the most common types of words overall. Conversation has a high density of verbs, unlike informative writing such as news and academic prose, which has a high density of nouns. Adjectives are linked to nouns, because they most frequently modify nouns. So informartive writing, which has the highest density of nouns, also has the highest density of adjectives. Adverbs, on the other hand, are linked to verbs. They typically describe circumstances relating to actions, processes, and states that are denoted by verbs. So conversation and fiction writing, which have the highest density of verbs,also have the highest density of adverbs.
Comparing function word classes in use : Striking differences in frequency of pronouns(high in conversation) and determiners(high in academic prose). Another difference is in the frequency of adverbial particles: this is the least frequent function word class in both registers, but it is much rarer in academic prose than in conversation.
Variation in the verb phrase across registers: active and passive voice
Passives are most common in academic prose, where they account for about 25 per cent of all finite verbs. Passives are also common in news. In contrast, passive voice verbs are rare in conversation. In academic texts passive voice verbs are especially common. Often, the human actor(or agent) is not important in academic writing. So the passive is useful: it reduces the importance of the agent noun phrase by putting it in a by-phrase or not mentioning it at all.
Clause patterns across registers
Discourse functions of that-clauses : That clauses in post-predicate position are by far the most common type of that-clause. They account for over 80 per cent of all that-clauses. These that-clauses typically report the speck and thoughts of humans. Post predicate that-clauses controlled by adjectives are less common than those controlled by verbs.