Pregunta vs. Cuestión
Pregunta is “question” in the sense of one that is asked, e.g.:
No tengo ninguna pregunta. - I have no questions.
Cuestión means “question” in the sense of an issue, a matter, or a topic.
Mi sueldo es una cuestión que no te importa.
My salary is a matter that doesn't concern you.
Esta noche vs. anoche
“Tonight” = Esta noche (“tonight”, “this night” or “this evening”).
“Last night” = Anoche.
¿Vas a ir al cine esta noche conmigo? - Will you go out with me tonight?
Yo hice la tarea anoche. - I did the homework last night.
“To enter/go in”: entrar en
Entrar means “to enter” or “to go [in]”; it must be used with a preposition —en or a— when followed by a place.
Entramos en el Parque. - We entered the Park.
¿Quién entró en la tienda?
Who entered the store?
“To realize”: realizar vs. darse cuenta de
"Darse cuenta de" (algo) is the standard way of saying “to realize (something)”, that is, when that mental light bulb suddenly turns on.
El profesor se dio cuenta de que yo era el único que estudiaba mucho. - The teacher realized that I was the only one that studied a lot.
Realizar is a real Spanish verb, but it means “to accomplish” or “to carry out”:
Quisiera realizar este filme en España. - I would like to carry out this film in Spain.
Televisión vs. televisor
Televisor is the TV set, whereas televisión refers to the industry or programming.
¿Por qué pasas tanto tiempo ante el televisor?
Why do you spend so much time in front of the TV (set)?
No me gusta la televisión.
I don't like TV.
Sólo vs. solo
Sólo is an adverb, a synonym for solamente, “only”. Solo (wihout the accent mark) is an adjective which means “alone”.
Sólo queremos vivir en Indiana.
We only want to live in Indiana.
Queremos vivir solos en el campo.
We want to live alone out in the country.
“By ... -ing”: el gerundio
The gerund (that is, the -ndo form) is used to express the idea of “by (do)-ing (something)”. (The preposition "por" plus the infinitive is not used in this way because it means “because of ... ing”.)
Aprendemos escribiendo.
We learn by writing.
“Because of ... -ing” or “for ... -ing” is often translated with "por" plus the infinitive; note that the past infinitive is frequently used if a previous action is indicated:
Lo queremos por ser tan amable.
We love him for being so kind [because of being so kind].
Lo encarcelaron por haber robado a mi hermana.
They put him in jail for robbing my sister [because of having robbed my sister].
“Ago”: Hace and hacía
If the verb describing the action is in the preterit or imperfect, hace (present tense of hacer) is used. If the action is given using the past perfect tense, hacía (the imperfect) is used:
Vi la película hace un mes.
Hace un mes (que) vi la película.
I saw the movie a month ago.
Me había quejado hacía un año.
I had complained a year earlier.
