Spanish language Q&A Forum

a ti TE gusta, NO? 

Just a terminology question, but why is this called "El Pretérito Perfecto Subjuntivo" instead of "El Presente Perfecto Subjuntivo"? I thought pretérito meant past tense? (It seems to mean past tense in the context of Pretérito Indefinido and Pretérito Imperfecto.) 

"Mathematics" can be taken as a singular noun. Therefore it seems that a correct format in Spanish would be 

"te gusta mathematics".

There was a question in one of the quizzes I took and it led me to this grammar topic (questions with qué):

Which flowers do you prefer?  

¿ _____ flores prefieres ? 

I put cuales in the blank, but was marked wrong, it said the answer was qué. 

I went to the lesson on cual/cuales (interrogative pronouns) and there was a sample sentence referring to flowers, using cuales prefieres.  

In the English translation to the quiz it uses which and I assumed that a select few flowers were being referred to, thus the answer should be cuales. It is a bit ambiguous. 

Is it interchangeable to say something like

Just as 'tal vez' and "quizás" are interchangeable, with no fast rules on them, is it the same for using quizá and quizás or is there some guide for when they can/can't be used?

also, is it impossible to use quizá/quizás/tal vez using future tenses? 
examples:

"Quizá iré a la biblioteca pasado mañana"
"Tal vez conocerás aquel varón cuando venga"
"Quizás recibiré una mejor evaluación cuando mejore mis debilidades en mi trabajo"

Oportunidad is a feminine noun. Why was it marked wrong when I wrote grande?  The correction was to gran.