Various verbs such as, cree, saber, pensar, tener, poder, deber, sentirse, necesitar are generally used in the imperfect tense. These verbs in most situations suggest a condition or a state of mind that already existed at the time in question rather than something that took place or began to happen at a particular point in time.

Notice the following differences en the English translation:

saber: No sabía eso antes; lo supe anoche. (knew; found out)

conocer: Yo no conocía a su tía; la conocí anoche en la reunión. (knew; met)

querer: Ayer quería ir al cine e invite a mi esposa, pero no quiso ir. (wanted); refused (negative)

Haber:

Había mucha gente en la fiesta. (There was / were present)

Hubo un terremoto ayer. (There was / were = these occurred)

Some verbs are used only in the imperfect when indicating past time.

ser in telling time - Era la una cuando llegué.
acabar de - Acababa de llegar cuando entró María.
decir - for anything printed or written – El telegrama decía eso.

estar – estuve when duration of time stated; otherwise, estaba

Imperfect indicators are words or phrases that in some way indicate repetitive or habitual actions in the past. Generally, they will be followed by the imperfect tense.

Review the three sets of expressions on the left which are generally associated with the Imperfect tense.