Fast pronunciation is very different from the dictionary form of the word. The English sound system varies from place to place, and from speaker to speaker. Speech usually consists of idea units. Sometimes idea units are complete sentences, but sometimes they are not. Written language is usually more correct and polished.
Speech contains many pauses and hesitations.
There are also fillers, meaningless words that give the speaker thinking time. Examples of fillers are um, well now, uh, let me see. Written language has none of those. Written language tends to be more conservative and old-fashioned. In speech a lot of things are not actually stated.