The imperfect usually describes a continuing action in the past. Not sure if you should use the imperfect or the preterite? DRETCH the verb!
When you are learning the simple past tenses in Spanish, it can be confusing to know when to use the pretertite or the imperfect. The following: DRETCH+1 is an easy way to know when to use the imperfect tense. Use the imperfect for:
Description:
Era una tarde estupenda.
It was a stupendous afternoon.
Repetition
Pasábamos los veranos al campamento del lago.
We spent the summers at the lake camp.
Everything before an interruption
Juan dormía cuando Josefa estornudó.
Juan was sleeping when Josefa sneezed.
NOTE: While everything before the interruption is in the imperfect, the interruption itself is in the preterite because it is a complete action. In the example Juan was sleeping. Josefa sneezed, each sneeze is a complete action unto itself. She may have sneezed once or several times.
Time or Weather
Eran las veinte. Llovía.
It was 8:00 pm. It was raining.
Customs
Bebían café con el postre.
They drank coffee with dessert.
Habits
Daba un paseo después de la cena.
He would take a stroll after dinner.
+1 Was/Were doing…
Comía. Conducía el tren. Los gansos volaban al sur.
He was eating. She was driving the train. The geese were flying south.
If you can't DRETCH your verb, then you'll want to use the preterite.
