The document discusses the past progressive and simple past tenses, noting that the past progressive describes ongoing past actions using "was/were + verb+ing" while the simple past describes single past actions using the past form of the verb. It also explains that the tenses can be used together to show one event interrupting another ongoing action or to emphasize multiple simultaneous past actions.

1. The Past Progressive Tense and the Simple Past Tense
 We use the past progressive to describe past situations or actions that were in
progress at some time in the past. The structure to form the past progressive
tense is:
Subject + aux. to be + main verb with ing + complement.
I was watching T.V last night.
 We use the simple past tense to show an action that occured one time and then
stopped. The structure to form the simple past tense is:
Subject + main verb in simple past + complement.
The telephone ran at ten o´clock.

2. The Past Progressive Tense and the Simple Past Tense
 We use the past progressive and the simple past tense to show one event
interrupting an action in progress.
I was watching T.V when the telephone ran.
When the telephone ran, I was watching T.V.
 We use the past progressive and the simple past tense to emphasize the fact that
two or more actions were in progress at the same time.
I was working in the garden while my wife was cooking dinner.
While I was working in the garden, my wife was cooking dinner.