Spanish language Q&A Forum

As stated by one example, "Yo conocí a Susana hace 6 meses."

However, as stated by another, "Hablé con Clara hace 2 horas." 

Why didn't the second example utilize "a"

Is it because "con" had already been used?

Como ves, mamá sabía que si ellos comían de ese fruto, pensarían que ya no la necesitaban.

Maybe start by listing the days of the week. None of the examples  given mention Thursday.

This was listed as B2, but required knowledge from C1 areas: Using dicho, dicha, dichos, dichas to say this/these (formal) and Using Spanish relatives el que, la que, los que, las que = the one/ones who/that (relative pronouns)

I am a bit frustrated with this lesson.  I guess my question is this: with my limited (A1) knowledge of Spanish, how am I supposed to know "that sometimes the feminine and masculine forms are the same" when repeatedly the test gives adjectives I do not (yet) know in Spanish?  

For example, placid.  I do not KNOW how to say placid in Spanish, thus how can I know if I should use the feminine adjective form or simply add mente?  The assumption of adjective knowledge doesn't work unless, as is sometimes done in the test, you GIVE the adjective form in the test question; example: Los coches son rápidos: van rápidamente.   In this example test question it is easy to understand rápidos (masculine form) will change to the feminine because I can SEE rápidos!  The frustrates me to get wrong when it seems to be testing me more on knowing a large range of adjectives in Spanish more than the specific assignment of adding the "ly" form! I don't see my scores getting better based on the lesson given.

El profesor llevaba hablando con el estudiante diez minutos cuando entramos en la habitación.

El profesor había estado hablando con el estudiante diez minutos cuando entramos en la habitación

Is there a general rule in Spanish about when the definite article must be used and when it can be omitted? Eg why do azúcar, sodio, carbohidratos and lácteos need the definite article but not pescado, marisco, granos and huevos? 

This is a helpful list.  Would you be able to add the infinitive forms, as you did with the table for the form "-yendo"?