Breakdown of Pour ce poste, ils ont porté des cravates.
des
some (plural indefinite)
ils
they (masculine/mixed)
pour
for
avoir
to have
Questions & Answers about Pour ce poste, ils ont porté des cravates.
The lesson is about using être in the past tense. Why does this sentence use avoir (ont)?
Because porter (to wear) is a regular, non-reflexive verb. The rule about using être applies to reflexive verbs where the subject acts on itself. If you wanted to say they dressed themselves, you would use a reflexive verb with être (like ils se sont habillés). But here, they are just acting on an object (ties), so it takes avoir.
Why does the sentence use ce poste? Doesn't poste mean the post office?
Since ils is plural, shouldn't porté have an -s at the end?
No, because this verb uses the helper verb avoir (ont). In the passé composé, you do not make the past participle agree with the subject when using avoir. You only add that -s for plural subjects when using the helper verb être (which is exactly what you must do with the reflexive verbs in this lesson).
Why is there a des before cravates? English just says "they wore ties".