D. The Past Continuous (in the middle of an action) is formed from the past tense of ‘be’ with the '-ing' form of the verb:
a. I was doing something = I was in the middle of doing something at a certain time. The action or situation had already started before this time, but had not finished.
D1. We use the Past Continuous to talk about the past:
a. with verbs which show change or growth. (e.g. The children were growing up quickly.)
b. for something which continued before and after another action. (e.g. The children were doing their homework when I got home. vs. I got home. The children did their homework. The children did their homework when I got home.)
c. for something that happened before and after a particular time. (e.g. It was eight o’clock. I was writing a letter. vs. At eight o’clock I wrote some letters. In July she was working in McDonald’s.)
d. to show that something continued for some time (e.g. My head was aching.)
e. for something that was happening again and again. (e.g. I was practising every day, three times a day.)
D2. often use the Past Simple and the Past Continuous together to say that something happened in the middle of something else. (e.g. Matt phoned while we were having dinner)
a. but we use the Past Simple to say that one thing happened after another (e.g. I was walking along the road when I saw Dave. So I stopped, and we had a chat)
D3. some verbs (know and want) are not normally used in the Continuous (e.g. We were good friends. We knew each other well. (not We were knowing)
Idiom 365
Don't teach your grandmother how to suck eggs: a person is giving advice to someone else about a subject of which they are already know more about than you
Example: You're teaching your grandmother how to suck eggs, boy. Your PM has been playing this sort of works since before you were born!