It is important to remember that Non-Continuous Verbs cannot be used in any "continuous" tenses.
FORM Past Continuous
[WAS / WERE] + [VERB+ing]
EXAMPLES:
I was studying when she called.
I was carefully picking up the snake when it bit me.
NOTE: When you are using a verb tense with more than one part such as Past Continuous (was picking), adverbs often come between the first part and the second part (was carefully picking).
IMPORTANT
Clauses are groups of words which have meaning but are not complete sentences. Some clauses begin with the word when such as "...when she called " or "...when it bit me." Clauses with the Past Continuous usually start with while. While expresses the idea "during the time." Study the examples below. They have the same meaning.
EXAMPLES:
I was studying when she called.
While I was studying, she called.
USE 1 Interrupted Action in the Past
USE 2 Specific Time as an Interruption
USE 3 Parallel Actions
USE 4 Atmosphere
USE 5 Repetition and Irritation with "Always"
USE 6 Intended in the past
Use the Past Continuous to indicate that a longer action in the past was interrupted. The interruption is usually an 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 a picnic, it started to rain.
Sally was working when Joe had the car accident.
While John was sleeping last night, someone stole his car.
In USE 1, described above, the Past Continuous is interrupted by an action in the Simple Past. However, you can also use a specific time as an interruption.
EXAMPLES:
Last night at 6 p.m., I was eating dinner.
At midnight, we were still driving through the desert.
IMPORTANT
In the Simple Past a specific time is used to show when an action began or finished. In the Past Continuous a specific time only interrupts the action.
EXAMPLES:
Last night at 6 p.m., I ate dinner.(I started eating at 6 p.m.)
Last night at 6 p.m., I was eating dinner.(I started earlier and at 6 p.m. I was in the process of eating dinner.)
When you use the Past Continuous with two actions in the same sentence, it expresses the idea that both actions were happening at the same time. The actions are parallel.
EXAMPLES:
I was studying while he was making dinner.
While Ellen was reading, Tim was watching television.
They were eating dinner, discussing their plans and having a good time.
In English we often use a series of Parallel Actions to describe atmosphere in the past.
EXAMPLE:
When I walked into the office, several people were busily typing, some were talking on the phones, the boss was yelling directions, and customers were waiting to be helped. One customer was yelling at a secretary and waving his hands. Others were complaining to each other about the bad service.
The Past Continuous with words such as always or constantly expresses the idea that something irritating or shocking often happened in the past. The concept is very similar to the expression used to but with negative emotion. Remember to put the words always or constantly between "be" and "verb+ing."
EXAMPLES:
She was always coming to class late.
He was constantly talking. He annoyed everyone.
I didn't like them because they were always complaining
We use was/were going to to say what someone
intended to do in the past but didn't to it.
EXAMPLES:
We were going to travel by train but then we decided to go by car.
I was just going to cross the road when someone shouted "Stop".