The duolingo pronunciation here is wrong. It should be the same as usual.

I believe when the following word starts with a vowel sound you actually do pronounce the "t". There was some other word I saw this done with I can't recall at the moment...

Her pronunciation is awful. No one in the french-speaking world would say "Essss til sur." It is "Ey-t-il sur." Many people have complained about this and Duo apparently just does not care.

Es-tu sûr?

No, I don't agree anymore, at least not if gaining competence in French is your ultimate goal. It is absolutely annoying and frustrating and seems unfair-- all of which would also seem to make it stick in one's head better than if it came right after Duo had introduced in a written example with a "hint" 10 seconds earlier. That's imho, after making it through the tree. If it doesn't annoy you enough to make you quit Duo, then it might actually be pedagogically effective.

Agreed!

damn fine plan!

Ikr, it seriously does ;-;

That is what I wrote. Is that not a valid way to ask?

Only if your "it" in the question "Is it safe?" refers to a specific object (or animal). Here's a THEORETICAL example:

• It's a beautiful neighbourhood = C'est un beau quartier

• But is it safe? = Mais est-il sûr ?

I say theoretical, because it's little likely someone would phrase it like that. "Est-il sûr ?" sounds too much like "Is he sure / certain?", that we'd rather re-use the specific noun : "Mais est-ce que c'est un quartier sûr ?".

But if the "it" is a general reference, or about a situation, then you must use "ce":

• Is it safe here? = C'est sûr ici ?

Yet, again, "sûr" is so much perceived in the sense of "sure / certain" that we don't often use it like "safe" is used in English. So the example just above would rather be expressed like this:

• Is it safe here? = On est en sécurité ici ? (word per word "Are we in safety here ?").

To get the u sound in sûr, try using the oo sound from the english word food

More like syure? The û sounds long and drawn out to me.

Vraiment !

"For sure" means "certainly", which is a different thing than what this sentence means : "is he sure" or "is he safe" (in the sense that he is faithful and keeps his word).

The previous example you mentioned required feminine sûre when it was not grammatically necessary to use feminine. In that case Duo was wrong and has yet to correct it. That construction you posted allows either masculine or feminine (sûr/sûre)

In this example, the presence of il in est- il does grammatically require a specific gender. Il being masculine, sûr is the required form. Here, Duo is correct.

« En » as a pronoun (it can have other roles) is the equivalent of “about it” or “some” (of it). So:

Sommes-nous sûrs ? Are we sure?

En sommes-nous sûrs ? Are we sure about it?

Il parle. He speaks.

Il en parle. He speaks about it.

http://www.wordreference.com/fren/sur sur = on

http://www.wordreference.com/fren/s%C3%BBr sûr = sure, safe