Spanish language Q&A Forum

What is the rule for using "mientras" or "mientras que"?

For example:

Escribo mientras que él come. Why can't I say: Escribo mientras él come.

Él habla mientras yo leo.           Why can't I say: Él habla mientras que yo leo.   

I cannot see any difference in syntax, usage or meaning between these two sentences, yet three native speakers have all told me they would only say the first, but could not tell me why or give me any grammatical rule.  Please help... someone/anyone.

Is it correct to say 'Desde cuánto tiempo vives aquí?' or do you have to say, 'Desde hace cuánto tiempo vives aquí'?

Gracias de antemano.

Carrie

Hi there, 

I have a question about the final sentence of the exercise. Why does 'hasta que' invoke the subjunctive here when the action is in the past? Thanks.

Ya que is said many times throughout and mostly seems to mean because. I have never seen this before, are there other things that ya que can mean? 

Does "postre" literally mean "pudding desert" as us suggested by the test answer? I would have thought another word would have been needed, or perhaps "flan" would have worked instead of "postre"?