Hi Chichi,

The standard expression is "Qu'est ce qui s'est passé ?" --> What has happened?

Se passer --> to happen / to occur.

To write "Savez-vous ce qui s'est passé" would be equivalent in the sense of "Do you know what has happened"

By writing "savez-vous qu'est-ce" you are doubling up on the question aspect and that is why this structure is not accepted.

This is how I see it  --  hope it helps.

Jim

Chichi,

Not sure if it is grammatically incorrect, but "Savez-vous qu'est-ce qui s'est passé ?" does sound rather 'clunky' to me in French, as would "(Do) You know what (it) is that has happened ?" in English.

But "Qu'est-ce qui s'est passé?" as a stand-alone question also sounds clunky to an English speaker, and yet we know it's correct. It's unclear to me why this structure is considered necessary on its own, but not after "savez-vous".

Qu'est-ce qui is a question structure.

Savez-vous is a question structure.

It would be very odd grammatically to use both in one interrogative sentence "Savez-vous qu'est-ce qui s'est passé?

This is the point that I am trying to make, hope it helps to clear this up for you.

Jim

But actually, it's quite normal for "savez-vous" to be followed by a question structure.

Où sont mes clefs ?

Savez-vous où sont mes clefs ?