Spanish language Q&A Forum

I have some confusion (and frustration) around use of definite articles in Spanish generally. In this lesson, I noticed what appears to be an inconsistency with this rule.

A mí, se me da bien contar chistes.

My question is, why is it not, "A mí, se me da bien contar los chistes".

Also, my other question concerns highlight #5 and use of "a".

The first example notes: "Se me da bien el tenis". [I am good at tennis], then later there's the example, "A mí, se me da bien contar chistes" [I am good at telling jokes.].  My question is the subject of both examples is first person ("I"), so why wasn't the first example written as "A mí, se me da bien el tenis". ?

Thank you for a clear explanation of these two issues.

Regards,

Pati Ecuamiga

Could you highlight this difference in the lesson in yellow or some sort of emphasis? 

If we want to express the same but in the negative, the structure changes to:

               llevar (conjugated) + sin + infinitive

 And also, if correct, please add the explanation that  the action  changes from  past participle to infinitive because sin is a preposition, and that prepositions are followed by infinitives, not past particples.