There are certain verbs in Spanish that change meaning when used in the preterite.
Conocer in its infinitive form means “to be acquainted with” or “to know a person or place.” If used in the imperfect, it means “used to know” or “knew someone or someplace” in the past. However the point in time the person or place was first known is a very specific instance, and therefore will be expressed using the preterite tense. In English, the first moment you knew someone is expressed by saying you “met” someone. The preterite forms of conocer are used to indicate the equivalent Spanish concept of “met.” Here are examples of conocer in the imperfect and preterite tenses:
- Imperfect: conocer = knew, was acquainted with
Yo conocía a Sergio de niño.
I knew Sergio as a child.
Tú conocías bien la ciudad de México .
You were well acquainted with Mexico City.
- Preterite: conocer = met, became acquainted with
Laura conoció a Manolo el 14 de febrero.
Laura met Manolo on February 14th.
Mis estudiantes conocieron Madrid durante nuestro viaje educativo a España.
My students became acquainted with Madrid during our Educational trip to Spain.
Saber means “to know a fact.” In the imperfect, it simply means “used to know” or “knew a fact” because knowledge of a fact was ongoing. When the moment the fact was first known is the focus of the sentence, it is stated in English as the instance when something was “found out.” The preterite forms of saber are the Spanish way of expressing the English idiomatic expression “found out.” Here are examples of saber in the imperfect and preterite tenses:
- Imperfect: saber = knew (some fact)
Él sabía la dirección de memoria.
He knew the address by heart.
- Preterite: saber = found out (some fact)
Él supo la dirección y fue a su casa.
He found out the address and went to her house.
Poder is translated “to be able.” It is always followed by a verb in its infinitive form. This concept is often expressed idiomatically in English as “can (is able to) do something” in the present tense or “could (was able to) do something” in the past.
The imperfect forms of poder express an ongoing ability to do something in the past. In a negative sentence, the imperfect tense of poder indicates an ongoing lack of ability to do something that was assumed or obvious. Used negatively in the imperfect, the indication is that one never specifically tried to do something but, rather, assumed the inability was ongoing.
Poder is used in the preterite tense to indicate a specific time when an ability to do something was not normally the case. In English a speaker says “I managed to do it” when something isn't typically do‐able.
In a negative sentence, the preterite of poder means that one could not do something at a specific time. In order for there to have been a specific time when one could not do something, the idea is that one tried and failed. Here are some examples of poder in the imperfect and preterite tenses in affirmative and negative situations:
- Imperfect affirmative: poder = was able, could do something
Constanza podía cantar como un pájaro.
Constanza could (was able to) sing like a bird.
- Preterite affirmative: poder = managed to do something
Esteban pudo subir la montaña.
Esteban managed to climb the mountain.
- Imperfect negative: poder = wasn't able, couldn't do something (assumed)
Nadie podía cambiar la ley.
Nobody could change the law.
- Preterite negative: poder = could not do something (tried and failed)
El atleta no pudo seguir.
The athlete could not continue.
Querer in the imperfect means “wanted or loved in an ongoing manner.” However, in the preterite, querer indicates that the wanting was to no avail. Used in the preterite negatively, querer is understood to mean that one not only didn't want to do something, but refused to. Here are some examples of querer in the imperfect and preterite tenses in affirmative and negative situations:
- Imperfect affirmative: querer = wanted something or wanted to do something (ongoing)
Benito siempre quería un barco.
Benito always wanted a boat.
- Preterite affirmative: querer = wanted something or to do something (at a specific moment in time)
Yo quise llorar cuando recibí la mala noticia.
I wanted to cry when I received the bad news.
- Imperfect negative: querer = didn't want something or to do something (ongoing)
Él no quería estudiar álgebra.
He didn't want to study algebra.
- Preterite negative: querer = refused to do something (at a specific time)
Mi padre no quiso conducir.
My father refused to drive.