French language Q&A Forum

I find it difficult with the article 'de'.  I have reviewed the grammar lessons here to brush up my concepts but when reading online articles I still flounder. e.g.  In this article, why do we write la dangerosité du Covid-19, en cas d'opposition. Should it not be de Covid and de l'opposition? https://www.rfi.fr/fr/am%C3%A9riques/20210529-%C3%A9tats-unis-vaccination-des-plus-jeunes-la-difficult%C3%A9-de-convaincre-parents-et-adolescents. Thank you in advance for helping clarify.  

how will i know where to use etre and where to use avoir?

What is the meaning of enchaînait as it applies in this particular sentence?:

Il enchaînait les conquêtes amoureuses en évitant à tout prix de s'engager.

It doesn't seem to fit the dictionary meaning.

so I was doing a quiz on Kwiziq and the question was "C'est amusant." means: to which I answered "it is funny". It gave me an 'almost there' mark and I don't get why. It says the right one is 'This is funny'. 

Jus

I did not get "The masculine adjectives chaud and froid never agree in gender or number, even if the person/thing it refers to is female or plural:" can someone please explain what they meant? maybe some examples? please

I wrote 'rencontrerez' for the future of the verb rencontre, & I got it right in the fill-in-the-blank exercise Horoscope de l'année (Le Futur); however, it doesn't seem to fit into the pattern for either regular -er and -ir verbs in the future or -re and -dre verbs in the future, and it directed me to this page, so I'm confused.

I constantly make errors when a infinitive follows another verb.  Sometimes the preposition 'de' introduces the infinitive as in "...decide de couper... " in the above exercise.   Sometimes the preposition  'à' intervenes as in "intéresser à".  Then there are verbs which take no preposition, for example "aller".  Finally, we have an example using the preposition pour, as in "...insisted pour payer..." in the exercise.  My question is "Are there patterns for these verbs or is it a matter of just learning by rote or just by listening to hundreds of conversations to remember the usage?" Thanks so much for your consideration. 

Would "un petit mot" work as a translation here? I feel like I've come across this much more often than "note", or maybe there's some nuance I'm missing?

Bonjour. J'ai une question. La lettre t en huit est muette lorsqu'on prononce un chiffre, par exemple 800. est-ce la même chose pour août par exemple le 10 août 2021 ?