My understanding of this is that an adjunct can be omitted, and the sentence will still be grammatical, whereas a complement cannot be omitted and leave a grammatical sentence. In the three sentences you listed, the bolded words can clearly be omitted from the third sentence, leaving a grammatical sentence, so the third is an adjunct. In the first two, however, if the bolded words are omitted, the sentences don't seem able to stand alone without them, so the first two are apparently complements.
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