Past Progressive

1. Time Clauses

1.1. To describe an ongoing action

1.1.1. While, When

1.1.2. While Mercedes was smiling her boyfriend kissed her.

2. Structure

2.1. Affirmative

2.1.1. S+Verb To Be+ (verb+ing)+C.

2.2. Negative

2.2.1. S+Verb To Be+Not+ (verb+ing)+C.

2.3. Interrogative

2.3.1. Verb To Be+S+ (verb+ing)+C+?

3. Functions

3.1. Describe actions in the past.

3.1.1. I was eating when my dog barked.

3.2. To describe an activity or event in progress over a period of time in the past.

3.2.1. What was happening during the part?

3.3. To describe background activities.

3.3.1. David was developing a cure for cancer.