Actuar
 

When you pronounce the infinitive of "actuar", the stress is on the "a", correct? Or is it on the "u"?

When you conjugate the verb in the present indicative, there is an accent on the "u". Why is that?

I believe I am correct in saying "actuar" has two syllables and the stress is on the last one: ac - TUAR. The "ua" forms a diphthong and "tuar" is pronounced as one syllable, so it's not pronounced "two-are", it's pronounced "twar".

The accent mark must be there because of the pronunciation. (Yo) actúo: ac-TU-o (three syllables). If it were pronounced as AC-tuo, then no accent mark would be needed.

So the accent mark indicates that the "u" and "o" do not form a diphthong.

I believe the above to be correct, if not, please correct me. :)

David's explanation is right. :)

Thanks for that explanation. My professors here in Argentina have talked a little bit about stressed syllables in "raízes" of verbs and in the different tenses. Is it outside the norm for a raíz to be stressed so differently in the infinitive than in the present indicative? To go from "-twar" to "-tu-o"? To go from a non-dipthong to a dipthong with the same letters?

For some reason I can't think of more examples at the moment, but I think this happens often enough to pay attention to it. And si no mal recuerdo, there are also verbs where there is a diphthong in the infinitive and it stays when conjugating, in other words, you don't add an accent mark. If I can think up some examples, I'll post 'em.

Thanks, David (and for the spelling correction). The one professor spent a couple of minutes going over preservation of stressed syllables in certain tenses and it was quite interesting. I want him to go over it again before we finish the course - made a lot of sense to me, so now my eyes are open to that kind of thing.

If he goes over any examples, post some of them back here-- for some reason I have a mental block and I can't think of any. :)

Yeah - he gave examples, but I didn't write them down. That's why I want him to go over it again. He tied it into spelling changes (like o->ue and e->ie, etc.) and compared the present indicative to the preterit. Great for my analytical mind! Whatever I find I will post! :)

Euphony, Lou Ann, is the keyword. ;)

I think someone else will have better explanations and examples, but it's just a matter of practice (and a conjugation manual) :p to know how to do it.
"Actuar" is an exception where the diphtong must be broken. Most of the verbs that have a similar ending like "licuar" or "evacuar", keep the diphtong when conjugated, even though many native speakers conjugate them wrongly.

Yo licúo licuo una manzana con agua.
I blend an apple with water.

Ellos evacúan evacuan el edificio.
They evacuate the building

Lou Ann:

Are you in Argentina.

If so, you're gonna have fun with the emphasis/accents... :)