1. Italian - Italy, Caserta, Gricignano d'Aversa, Civil Registration (Comune), 1809-1929
First, the similarities to Latin and French should be pretty clear. We can conclude that it's a Romance language. First, let's compare the words for "year" in a few Romance languages.
Catalan anyBased on the forms above, the language is either Italian or Portuguese. Now let's look at the words for "thousand".
Italian milleSo, it's Italian.
2. Dutch - Netherlands, Gelderland Province Civil Registration, 1811-1950
First, the similarities to English and German show that it's a Germanic language. Let's look at word for "year". In many languages, the English Y sound is represented by J.
3. Portuguese - Portugal, Coimbra, Catholic Church Records, 1459-1911
This is a little tricky. In modern Portuguese "year" is spelled with one N (ano), but in older records you will find it with two Ns (anno). If possible, it is useful to consult an older dictionary like this one available through Google Books. In this case, we go through the same procedure as with Italian. Another good marker of Portuguese is do, which is a combination of the preposition de "of" and the masculine singular article o "the".