The past continuous tense of any verb is composed of two parts:

the verb to be (was/were), and the main verb + ing.

(We , you , They) were singing

(I, he, she, it) was dancing

The past continuous tense is used to express continuous, ongoing actions which took place in the past.

He was traveling in Europe last summer.

We use the past continuous tense to speak about more temporary situations and actions .

I was watching television at 10 o'clock last night.

For examples : I saw you in the park yesterday. your sitting on the grass and reading a book .

For examples : We knew each other well. (Not we were knowing each other)