Cleft sentences: c'est… qui, ce qui… c'est
CEFR C1
The passé simple: for reading, not speakingRecognising passé simple forms when reading and knowing which infinitive they belong to…Inversion after a fronted adverbInverting the subject after the adverbs that require it, adding the linking -t- where…Connectors for formal argumentUsing the connectors that carry a French argumentative text, and telling them apart from…The imperfect subjunctive, for readingRecognising the forms when reading and knowing which spoken tense they match, without…The impersonal constructions of formal FrenchOpening the sentence with impersonal il and giving each phrase its preposition and mood.Accents and the cedillaPlacing é, è, ê and ç correctly, and knowing that in French an accent changes the sound…The rule, in three lines
French word order is rigid, so to highlight something it does not move it: it wraps it. C'est… qui for the subject, c'est… que for everything else, and ce qui / ce que / ce dont… c'est when what is highlighted is a whole idea.
The usual slip. Highlighting by moving the word, as your own language does, and ending up with a badly ordered French sentence. Or choosing qui where que belongs.
Why it catches you out. English has both the cleft —It was Marie who said it— and plain stress on the word, which French cannot use. So the pattern is familiar but has to be used far more often, and the agreement of «c'est moi qui suis» has no English equivalent.