Subjuntivo y impersonal
- Se (hacer) fotocopias en color, My own anwer is (hizo) I think is just a impersonal frase.
2.Pasaremos a realizar una serie de entrevistas con los candidatos que (reunir) los requisitos. Could I use subjuntivo (reúnan)? o it's just a indicativo?
3.Insiste en que no (preocuparse,nosotros). I use subjuntivo (nos preocupemos),but I look up dictionary that there is a sentence"Insiste en que tienes la culpa." Does it mean that Insistir en que +indicativo?
4 Answers
First, you should use the plural conjugation because "fotocopias" is plural.
If you are making passive voice sentences (as you did) that is true. If you are making an impersonal statement you must use the singular form. (excluding impersonal they which does not use the se at all)
Color copies are made. = Se hacen fotocopias en color.
One makes color copies.= Se hace fotocopias en color.
con los candidatos que reúnan los requisitos. (Subjunctive because we don't yet know who has met the requirements)
With adjective clauses this is referred to as an indefinite antecedent. We don't know who or if any of the candidates meet the requirements.
Some adjective clauses require the indicative, while others need the subjunctive. What's the difference? Reality and existence of the noun described by the adjective clause.
How do you know what tense you are supposed to use?
Se (hacer) fotocopias en color, My own anwer is (hizo) I think is just a impersonal frase.
First, you should use the plural conjugation because "fotocopias" is plural. What I don't know is what tense you are supposed to use.
Color copies are made. = Se hacen fotocopias en color.
Color copies were made. = Se hicieron fotocopias en color.
Color copies have been made. = Se han hecho fotocopias en color.
Color copies will be made. = Se harán fotocopias en color.
etc.
Pasaremos a realizar una serie de entrevistas con los candidatos que (reunir) los requisitos. Could I use subjuntivo (reúnan)? o it's just a indicativo?
It is important to know what tense you need to use because the decision to use the indicative or subjunctive mood depends on the tense.
...with the candidates that (may) meet the requirements = ...con los candidatos que reúnan los requisitos. (Subjunctive because we don't yet know who has met the requirements)
...with the candidates that have met the requirements = ...con los candidatos que han reunido los requisitos. (Indicative because requirements have been met already by certain candidates.)
Insiste en que no (preocuparse,nosotros). I use subjuntivo (nos preocupemos),but I look up dictionary that there is a sentence"Insiste en que tienes la culpa." Does it mean that Insistir en que +indicativo?
Insiste en que no nos preocupemos. Subjunctive is correct here because it expresses a wish/desire/command.
Insiste en que tienes la culpa. Indicative is correct here because he is simply stating a belief that you are at fault. That is not cause for using the subjunctive.
Yes the first one is a good candidate for the subjunctive because you are speaking about people who may or may not exist, the actual individuals are as yet unknown.
And the second one is good for the subjunctive too -putting the preocuparse in the subjunctive mood stresses the fact that someone else is insisting that we not worry rather than stating that we are not worrying (although this may indeed be the case) 
Hope that helps!
If you are making passive voice sentences (as you did) that is true. If you are making an impersonal statement you must use the singular form. (exlcuding impersonal they which does not use the se at all)
Completely agree. I assumed passive voice because her original guess was "hizo" and "One made color copies", while I'm sure one can think of a valid example of using this construction, is not a very common way of saying things.
