Normal word order in French and English requires that the subject be placed before the verb:
We speak about inversion, when, for whatever reason, the subject comes after the verb. This happens in both English and French, but it is far more common in French, and can lead to serious misunderstandings.
More about this last case below.
English uses inversions for questions with just a few common little verbs:
Will your mother come?
*Rings the phone?
The asterisk precedes an ungrammatical form.
In French, inversion in questions affects all verbs. If the subject is a Pronoun, things are simple,
If the following pronoun would cause two vowels to come together, an "epenthetic" -t- is inserted, which has no meaning but changes the pronunciation:
If the subject of a question is a noun, rather than a pronoun, things become more complicated: an extra pronoun is added after the verb.
There is an alternative way to ask a question, which avoids the inversion. This uses the little phrase est-ce que. It is extremely common, especially in spoken French, but in the written forms you'll be looking at, inversion is much more common.
2. Inversion in relative clauses
In a relative clause, after a relative
pronoun, other than qui, inversion is usual,
though not obligatory. (You can say Le saumon que les Canadiens
mangent.) This is what happens in C'est
le maître qu'a attaqué le
chien, quoted above.
3. Inversion after initial adverb.
In French, inversion is common when an adverb is in initial position (i.e. at the beginning of a sentence or clause), especially the adverbs peut-être, sans doute, or aussi (which means so, or therefore when it's placed at the beginning of a clause). Make sure you don't mistake these inversions for questions.