توضیح :

زمان گذشته استمراری (past continuous)، در زبان انگلیسی، برای صحبت در مورد وقایع گذشته (past events) به کار می رود که برای دوره ای از زمان (period of time) اتفاق افتاده اند.

ما از گذشته استمراری (past continuous) برای تاکید بر ادامه داشتن آن فرآیند، استفاده می کنیم. اگر می خواستیم که تنها در مورد آن اتفاق، به عنوان حقیقتی در گذشته صحبت کنیم، از گذشته ساده (past simple) استفاده می کردیم.

• While I was driving home, Peter was trying desperately to contact me.
• Were you expecting any visitors?
• Sorry, were you sleeping?
• I was just making some coffee.
• I was thinking about him last night.
• In the 1990s few people were using mobile phones.

ما اغلب از گذشته استمراری (past continuous) برای توصیف یک کار پس زمینه (background action) ، زمانی که چیز دیگری اتفاق افتاده است، استفاده می کنیم :

• I was walking in the street when I suddenly fell over.
• She was talking to me on the phone and it suddenly went dead.
• They were still waiting for the plane when I spoke to them.
• The company was declining rapidly before he took charge.
• We were just talking about it before you arrived.
• I was making a presentation in front of 500 people when the microphone stopped working.

منبع ترجمه و تالیف :

http://englishgrammarsecrets.com/pastcontinuous/menu.php