Past Simple VS Past Continious

Past simple: we use the Past Continuous to indicate that a longer action in the past was interrupted. 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?

Past continuousd: we use the Simple Past 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 specific time, but they do have one specific time in mind.

Present Perfect

The Present Perfect is a verbal tense if you use the auxiliar verb Have/Has (to have),
We CAN use the Present Perfect with unspecific expressions such as: ever, never, once, many times, several times, before, so far, already, yet, etc.

Positive: You have already watch the tv.

Negative: He hasn't watch the tv yet.

Interrogative: have they watch the tv yet?