No estoy seguro...

Question

In the statement: "Estoy seguro de que es seguro." why is the "de" needed?

Answer 1

I once had it explained to me as follows, however, I am not sure whether the same would apply to your example.

When you say "es un señal que...," the que modifies the noun señal, making it a sort of subject of the following clause. That is, it tells the reader that you are going to say something about the señal itself, as opposed to referring to something the señal indicates.

For example: Es un señal que llama la atención. It's a sign that catches your attention.

On the other hand, in "es un señal de que...," the following clause doesn't refer to the señal itself, but rather to what is being indicated by the señal.

For example: Es un señal de que la situación está mejorando en Irak. It's a sign that the situation is improving in Iraq.

Oh, I think that this explanation is interesting and valuable even if it does not apply exactly here. But it does apply here, doesn't it? - Janice, Sep 13, 2009

Thanks! That is really interesting and a big help. - estudiante9871, Sep 13, 2009

Answer 2

I think that the "de" translates the thought we would express in English with the word "about".

de que... de = about ....que = that which.....(or what)

But a native speaker can perhaps confirm or explain this better.