Es la forma gramatical utilizada para una acción que estaba realizándose o un evento que sucedió en un momento determinado del pasado, pero que está inconcluso. Para ello se utilizan el verbo to be en tiempo pasado was o were + raíz del verbo principal - al que se la añade la partícula -ing:
✦ I was eating
✦ they were running.
✦ She was arriving by car.
See the following examples:
Tenga en cuenta que el verbo to be, en este caso el pasado was / were (las únicas formas de pasado), se pueden escribir con contracción: was not = wasn't / were not = weren't (se utiliza de forma general en la lengua hablada, pero también en los escritos informales).
A continuación veremos algunas de las formas de utilización del past continuous
-Al comienzo de una historia:
✦ On Sunday he was flying to New York, then...
✦ During the last holiday season they were enjoying their time together...
✦ In 1945 I was flying a war plane, I was a pilot in those days...
-Para algo que continua antes y después de la acción:
✦ My girlfriend was preparing dinner when arrived to my flat.
✦ Police officers were waiting for us when we entered the stadium.
-Para describir un momento específico:
✦ On 4th July 1975 I was walking all day in Central Park, New York.
✦ In summer my wife and I were living in Paris.
✦ On 6 December 2017, we were celebrating the Spanish Constitution Day.
-Para expresar casos de forma repetitiva:
✦ He was taking drugs regularly.
✦ My wife was improving her cooking in the catering school.
✦ They were always chatting on Sunday afternoon.