Spanish language Q&A Forum

Why whenever I use sobre in a sentence its followed only by 'la/el'? These examples are taken from the course I'm doing on Duolingo. 

E.g. El gato esta sobre la mesa. 

But if I use debajo its followed by 'de la/el'. 

Mi celular esta debajo de la ropa. 

Is there a reason for this? 

Why does one use just 'la/el' but the other needs the 'de' to be marked correct? 

Of course numbers are read all kinds of ways, but I was always taught that in reading a number without a decimal (i.e., "20, 354") the word "and" is not to be used. Thus, your example "20,354" would be vocalized as:  "twenty-thousand, three hundred fifty-four". No "and".

Pati Ecuamiga

Proteger becomes protejo in first person present tense. Can’t you pretty much always dro the o and have the stem for the present subjunctive? For me, it is easier to remember.

Hola Inma, 

Very comprehensive and has cleared up a lot of my confusion. Saludos. John

Shouldn't it be groupos indígenos with an "o"?

Why isn't "las" used to modify both bicicletas and cintas de correr? I thought bicycles and treadmills were a general class of equipment, and not a specific bike or a specific treadmill. Thank you.