"My father is always calm."
Translation:Meu pai está sempre calmo.
At this point it's a bit tempting to start trolling a bit around lack of (sense of) nuances in English ;-) However, English is quite a "robust" language, and personally, I think much of its success in conquering the world lies exactly in this; Even if you're quite a novice, you are prone to survive fairly well with English. To be REALLY GOOD in English is very hard, and lots of nuances exist through the extremely rich vocabulary and many fun concepts as e.g. collective nouns. The English grammar is very simple, even no genders for nouns, simple verb conjugation and the building of a sentence is not critical (i.e. the order of the words). (They main need is to order the words well enough for the listener/reader to understand who/what is the subjective vs. objective.) In English, 'to be' is a single verb, as opposed to the latin 'ser' and 'estar'. In PT, the order of the words will impact more since, as danmoller already said above, 'sempre' points to the time (verb) or state (adjective). This would also impact the selection of 'ser' vs. 'estar' as the former is used for something permanent whereas the latter is used for a more temporary state. Now I should add the usual disclaimer that neither English nor PT is my native tongue, but my sense/understanding is this:
If I say "Meu pai é sempre calmo", it would more or less describe one of his permanent features. He is a calm guy, and it's never changing. (In this case I use 'ser', and 'sempre' points to the adjective, 'calmo'.)
If I say "Meu pai sempre está calmo", I'm changing from a description of his permanent feature to telling how he reacts in given (temporary) situations. In this case 'sempre' points to 'está' and indicates something more like everytime (a situation arises, my father keeps calm).
Again, I'm not native, but I would anticipate certain combinations to be void & meaningless (or gramatically illegal), such as "Meu pai sempre é calmo" which is strange because the use of 'ser' indicates a permanent feature whereas 'sempre' points to 'é' indicating a series of (temporary) situations, which would require 'estar' to be used rather than 'ser'.
I don't know if this made any sense or was at all helpful, but I'm eager to hear any native comment upon my sensing of the nuances here! :-)
Two of the sentences in the multiple choice use the adjective "tranquilo".
In English, I would use the word tranquil to describe land/seascape or conditions - non-animate objects that are nonetheless subject to change.
I would use the word calm to describe people or animals as well as the inanimate (calm conditions, calm seas, &c)
Is there the same sort of nuance in Portuguese between the adjectives tranquilo and calmo?