The three French verb constructions which include some form of être plus a past participle usually require grammatical agreement of the past participle with the subject.
Approximate numbers are very useful for talking about generalities, making estimates, and just flat-out guessing. English only has one approximate number, content to use "about" in front of cardinal numbers any time a guess is required. In contrast, French has about a dozen approximate numbers.
The prepositions après and derrière have somewhat similar meanings, which of course means that students sometimes get them confused. Learn the difference between après and derrière to put all of this confusion behind you.
There are three types of French articles (definite, indefinite, and partitive), and it's not always easy to know which one you need. Here's a detailed comparison to help you decide.
Auxiliary verbs are also known as helping verbs, because they help form compound conjugations. The key thing to remember about compound conjugations is that it's the auxiliary verb which conjugates for the required tense or mood; the main verb is always a past participle.
The prepositions avant and devant have somewhat similar meanings, which of course means that students sometimes get them confused. Learn the difference between avant and devant to get in front of any potential confusion.