Here are some examples of situations where a sentence is used in the past and how you can detect it. When reading these examples, observe certain key words that demonstrate an action done in the past. These words are either in the past tense or describe something done in the past.
A noise woke Sarah.
KEY WORD(s): Woke
The verb WOKE is in the past therefore the verb is PRETERITE. The action is done with and finished.
Another situation... Sarah walked down the hall to the peculier sound.
KEY WORD(s): Walked
the verb Walked is in the past therfore the verb is PRETERITE. It is over and done with as well.
Last Example: As Sarah turned the hall, she saw her cat, Muffin who licked the milk out of the tipped over bowl.
KEY WORD(s): Turned
All of these verbs are done i the past and therefore PRETERITE as well!
These key verns help you indicate whether its Imperfect or Preterite.