Typically, yes/no questions are formed by ending the sentence with rising intonation.
As we've already seen with tu and vous, French has different
levels of formality. These different levels of formality are also expressed
when asking questions. Inverting the subject and verb is formal.
When a verb ends in a vowel and is followed by il, elle,
or on, a 't' is inserted between the verb and the noun.
Usually when je is the subject, questions are not formed through inversion
except with a few short monosyllabic verbs (aller, avoir, devoir, dire,
être and pouvoir)
Instead, when je is the subject, questions are typically formed by
'fronting' with est-ce que.
Fronting a question with est-ce que, is also very common when the
subject isn't je.
If a question is asked with a negated sentence, you should contradict the assumption