"sich bei etwas sicher sein" or "sich etwas[Gen.] sicher sein"

Question

In a German text I had written, one of its sentences has been corrected as follows :

Zum Beispiel schreibe ich Wörter, bei deren Aussprache ich mir nicht sicher bin, zwischen eckigen Klammern.

In my original sentence, I had written :

Zum Beispiel schreibe ich Wörter, deren Aussprache ich mir nicht sicher bin, zwischen eckigen Klammern.

As far as I know, the correct expression is "sich etwas[Gen.] sicher sein". I don't understand the meaning of "bei" in this sentence and why it is necessary.

Could anyone please explain to me why it's "bei deren" and not just "deren" ?

Answer 1

Well, there is a difference in meaning which may become more obvious when we shorten these sentences to:

Ich bin mir bei der Aussprache ^Dat. sicher.

This is exactly what we want to say: "I am confident on pronouncing".

Ich bin mir der Aussprache ^Gen. sicher.

This may be taken as identical to the above but there is a different meaning when using genitive case: "I am sure of a pronunciation." In your examples above we make clear that we use the dative case by introducing the preposition "bei".

This can also be seen in the following examples:

• Er ist sich ihrer Liebe sicher. - He is sure she will love him.
  Er ist sich bei ihrer Liebe sicher. - He is sure her love is true.
• Sie fühlt sich ihres Einkommens sicher. - She feels her income is safe.
  Sie fühlt sich bei ihrem Einkommen sicher. - She feels safe with her income.