Through the use of these complex sentence constructions with informationally vacuous subjects, English is able to maintain both a topic-comment sentence structure and a SVO syntax. Focus constructions emphasise a particular piece of new or salient information within a sentence, generally through allocating the main sentence level stress on the focal constituent. For example, "the girl was stung by a bee" (emphasising it was a bee and not, for example, a wasp that stung her), or "The girl was stung by a bee" (contrasting with another possibility, for example that it was the boy). Topic and focus can also be established through syntactic dislocation, either preposing or postposing the item to be focused on relative to the main clause. For example, "That girl over there, she was stung by a bee", emphasises the girl by preposition, but a similar effect could be achieved by postposition, "she was stung by a bee, that girl over there", where reference to the girl is established as an "afterthought". Cohesion between sentences is achieved through the use of deictic pronouns as anaphora (e.g. "that is exactly what I mean" where "that" refers to some fact known to both interlocutors, or "then" used to locate the time of a narrated event relative to the time of a previously narrated event). Discourse markers such as "oh", "so" or "well", also signal the progression of ideas between sentences and help to create cohesion. Discourse markers are often the first constituents in sentences. Discourse markers are also used for stance taking in which speakers position themselves in a specific attitude towards what is being said, for example, "no way is that true!" (the idiomatic marker "no way!" expressing disbelief), or "boy! I'm hungry" (the marker "boy" expressing emphasis). While discourse markers are particularly characteristic of informal and spoken registers of English, they are also used in written and formal registers. English is a rich language in terms of vocabulary, containing more synonyms than any other language. There are words which appear on the surface to mean exactly the same thing but which, in fact, have slightly different shades of meaning and must be chosen appropriately if a speaker wants to convey precisely the message intended. It is generally stated that English has around 170,000 words, or 220,000 if obsolete words are counted; this estimate is based on the last full edition of the "Oxford English Dictionary" from 1989.