Spanish language Q&A Forum

to summarise some of the info provided in the comments.

am i right to say the below:

Le encantan los documentales de historia, que/lo que/lo cual (yo) encuentro aburrido = I find [the fact] that she loves history documentaries boring.

Le encantan los documentales de historia, que/los que/los cuales (yo) encuentro aburridoS (agreement of the adjective is necessary here) = I find history documentaries boring.

meaning to say, que = lo que = lo cual are interchangeable and replaceable with no change in meaning. same for que = los que = los cuales ? 

Hoy invito yo, así que escoged ________ os guste.

This sentence has subjunctive so am i right to say it means = choose whatever you like?

if it means = whatever you like, then why is cual or cuales wrong for this sentence?

thanks

under this section, the quiz showed a question as below.

Estoy intentando que ellos nos ________ una oportunidad.

i am not sure why does intentar trigger subjunctive.

is this because it contains uncertainty? so if im using other similar verbs such as probar or whatever scenario of trying to do something, i will need to use subjunctive?

I'm not sure I understand why the usage is "mensajes clave" vs. "mensajes claves"

Is clave in this context an adjective?  If so, shouldn't it agree in number with the noun?
mensajes clave vs. mensajes claves

As an example, wouldn't  "important messages" be plural? e.g. "mensajes importantes"? 
Why does "clave" stay singular when "mensajes" is plural?

I must have missed this grammar lesson on adjectives like Clave :-)

When talking about past actions we can also use it with the subjunctive, but this makes it sound more formal.

Se echan a reír -  laughing. What does echarse mean in this case ?

Va vestido elegantemente, va pegando a los pobres. I can’t find lesson note on this or in dictionary. May I know if this is a grammar point such as ver + participles to mean something ?

This rule does not work with amable.  If you do an exercise on superlatives with a question on "amable" before you read the lesson on -co, -go, -ble, and -z endings you will make a mistake. Perhaps this lesson should should point out that -ble endings  are an exception.  

Of course I will always remember the rule now after spending some time trying to discover why  "amablísimos" was wrong.