French
French adjective placement follows the noun in most cases ('une voiture rapide', 'a fast car'), which forces a systematic reordering of noun phrases. Some adjectives like 'grand', 'beau', 'petit' precede the noun but change meaning depending on position: 'un grand homme' (a great man) vs 'un homme grand' (a tall man). This positional semantics has no direct equivalent in English.
French verb tenses do not map cleanly to English. The passé composé functions as both the simple past and the present perfect: 'j'ai mangé' can mean 'I ate' or 'I have eaten' depending on context. The imparfait covers habitual past ('I used to'), continuous past ('I was doing'), and descriptive past simultaneously. English splits these into distinct tense constructions.
French maintains grammatical gender across all noun phrases, requiring agreement of determiners, adjectives, and past participles. English abandoned grammatical gender centuries ago. When translating, this means recovering grammatical information that English speakers never had to learn: whether 'the problem' is masculine or feminine matters in French but is invisible in English.