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Past Continuous
FORM
 Sujeto + was/were + el verbo principal acabado en "ing".
Use the Past Continuous to indicate that a longer action in the past wasinterrupted. The interruption is usually a shorter action in the Simple Past. Remember this can be a real interruption or just an interruption in time.Examples:
* I was watching TV when she called.
* When the phone rang, she was writing a letter.
* While we were having the picnic, it started to rain.* What were you doing when the earthquake started?
* I was listening to my iPod, so I didn't hear the fire alarm.
Simple Past
FORM
Use the SimplePast to express the idea that an action started and finished at a specific time in the past. Sometimes, the speaker may not actually mention the specifictime, but they do have one specific time in mind.
Examples:
* I saw a movie yesterday.
* I didn't see a play yesterday.
* Last year, I traveled toJapan.
* Last year, I didn't travel to Korea.
* Did you have dinner last night?
Past Perfect
The Past Perfect expresses the idea that somethingoccurred before another action in the past. It can also show that something happened before a specific time in the past.
Examples:
* I had never seen sucha beautiful beach before I went to Kauai.
* I did not have any money because I had lost my wallet.
* Tony knew Istanbul so well because he hadvisited the city several times.
* Had Susan ever studied Thai before she moved to Thailand?
* She only understood the movie because she had read the book.