Past Tenses

Take a look at these examples:

The ship was sailing when it hit the iceberg.

I was walking across the street when the accident happened.

We were watching TV when the lights went out.

As you can see, two actions are described in each sentence and two different tenses are used. For the longer action that was interrupted the past continuous is used, while for the shorter one that interrupted the action in progress in the past - the past simple is used. 

Time markers used: while (= dok), as (= dok), when (= kad).

You already know that the past simple of regular verbs end in -ED and that irregular verbs must be learned by heart. You should also remember that the past continuous consists of the past form of TO BE (WAS with I, he, she, it; WERE with we, you, they) and the present participle/-ING form of the main verb. Some verbs only take the -ING ending (watching, going, playing, trying), others double the consonant (stopping, sitting, cutting, swimming, shopping) or drop the -e and add the -ING (coming, having, driving, making, moving). But, there are some irregular present participle forms as well (lie --> lying, die --> dying).

Here are a few more examples:

Mary was cooking while John was reading a book. (2 actions happening at the same time in the past; both in the past continuous)

As I was getting out of the bus I fell. (a longer action interrupted by a shorter action)