Spanish language Q&A Forum

In a sentence like "I don't know what he knows" or "I don't know if he knows" the sentence can express doubt or merely be a statement of fact. Wouldn't the choice of whether to use the indicative or subjunctive depend on what you are trying to convery (ie:  "No sé lo que sepa" if I am trying to express doubt about what he knows but "No sé lo que sabe" if I am simply stating the fact that I don't know what he knows)?

No entiendo por qué el Rey hizo eso. Él lo hizo porque quiso

Unless the Spanish have a definition of "conjunction" that differs from the one I've always understood, both "por qué" and 
"porque" are both being used as conjunctions in those sentences. It is the sense of their use which differs.

Can these two uses be distinguished in spoken Spanish and if so, how?

what is a plural spanish word for usted?

When I selected "Yo vivo en" it was marked incorrect.  There was an option for "Vivo en" but I chose to include the Yo.  Is "Vivo en" the best answer?  Is that why it was marked incorrect?

Tu novia y tú habéis estado comprometidos hasta este año.Your girlfriend and you have been engaged until this year.

The meaning is unclear to me — are they no longer engaged?  

Then, in my opinion,  the English should be:

..Your girlfriend and you.were engaged until this year, not have been. But maybe I do not understand what is being expressed in Spanish. In any case, the English sentence is not clear.