1. The past progressive is used to describe an action that was in progress (happening) at a specific time in the past.
A: What were you doing at 6 p.m. last Friday?
B: I was watching TV.
1a. The simple past, on the other hand, is used to describe a completed action at a specific time in the past.
I went to bed at 10 p.m. last night.
2. The past progressive is used to describe an action that was interrupted by another action. The action that
interrupts is in the simple past. Use while
with the action in the past progressive or when with the action in the simple past. The choice of
while or when
depends on what you want to emphasize. While
emphasizes the action in progress (the background action) and when emphasizes the interrupting action. Also, the
clause at the beginning of the sentence is the more emphatic.
If the clause with while or when comes at the beginning of the sentence, put a comma
after the clause.
Professor Tanaka was correcting papers when the bell rang. When the bell rang,
Professor Tanaka was correcting papers.
OR
The bell rang while Professor Tanaka was correcting papers. While Professor Tanaka was
correcting papers, the bell rang.
3. The past progressive is used in both clauses with while or when to describe two
simultaneous actions in the past.
Professor Tanaka was correcting papers while the students were
taking the exam. While the students were
taking the exam, Professor Tanaka was
correcting papers.
4. The simple past is used in both clauses with when to indicate that one action was the result of
another (cause and effect). The clause with when indicates the cause.
When the bell rang,
the students handed in their papers.
The students handed in their papers when the bell rang.
6. The past progressive describes temporary
states, whereas the simple past describes permanent states. For example:
He taught at Harvard for thirty-five years.
(permanent situation)
He was teaching at Yale during the fifties.
(temporary situation)
He was teaching at Yale when I met him.
(temporary situation)
7. The past progressive describes incomplete
actions, whereas the simple past describes complete actions.
I was reading a book last night. (I
didn't finish the book--incomplete.)
I read a book last night. (I finished the
book--complete.)
8. The past progressive indicates that the action was in progress
(happening) during the whole period mentioned in the time
expression.
I was working on my term paper yesterday.
(the whole day)
It was raining yesterday. (all day
long)
8a. The simple past, on the other hand, indicates that the action was
completed in the time period mentioned.
I worked on my term paper yesterday.
(probably not the whole day)
It rained yesterday. (only part of the
day)
