Spanish language Q&A Forum

How is the future perfect used for probability in the past

My question and answer: How would you say "For many years I have done Tai Chí"?  I picked "Desde hace muchos años hago Taichí.  But it says the correct answer is Desde much años hago Taichí.  

Looking at the lesson that the link takes me too, I only see to use Desde when the time is specific like 1 year.  

Please help.

Tiene    and  usted tiene

Both are correct, as the usted is optional to phrase in the sentence.

But it is marked incorrect.    Grammatically it is correct, so I believe it shouldn't be marked incorrrect.

Hello. Would the following be acceptable as translation?
"ya que su vida se refleja en cada uno de ellos"

The kwiziq page "Ser vs Estar in Spanish: Using ser in Spanish (not estar) to talk about time, days, dates and seasons" (Ser vs Estar in Spanish: Using ser in Spanish (not estar) to talk about time, days, dates and seasons) says

   Hoy es lunes.  =  Today is Monday.  ("Today" is singular.)

but

   Son las tres de la tarde.  =  It's three o'clock in the afternoon.  ("It" is plural.)

Why are these different?

Are there any guidelines for the use of the phrase '' ''los demás'' versus ''los otros''  this? Many thanks