It's said in phonetic books that some word classes are stressed (i.e. lexical words: nouns, adjectives, verbs, adverbs) and some are not (particles, conjunctions, prepositions, pronouns, auxiliary verbs...). It's also said that Germans speak in intonational phrases, and each intonational phrase has one nucleus and the nucleus occurs normally on the last lexical word in an intonational phrase, unless that word is a verb. In the following examples the stress occurs on 'Deutschland' in both sentences:
Er schreibt ein Buch über Deutschland.
Er hat ein Buch über Deutschland geschrieben.
But where would the stress naturally occur in case we do not have a last lexical word or that the last lexical word is a verb? Examples:
Sie hat ihn vergessen.
Sie sah um sich.
Es ist recht still um ihn geworden.
Darum habe ich nicht schreiben können.
P.S. Of course we can stress any word at all in any sentence contrastively to point it out, but my question is all about natural speaking.