The past progressive aspect also expresses an incomplete or ongoing action or state. The incomplete or ongoing action or state began, continued, and ended in the past but over a longer period of time than the completed actions expressed by the simple past tense. Take for example the following two sentences:
- The phone rang when the woman entered her office. (simple past)
- The phone was ringing when the woman entered her office. (past progressive)
The first sentence The phone rang when the woman entered her office expresses two separate events: the phone rang and the woman entered her office. The phone ringing and the woman entering her office just happened to occur simultaneously. The second sentence The phone was ringing when the woman entered her office also expresses the two events of the phone ringing and the woman entering her office. However, the use of the past progressive in the second sentence indicates that the phone was ringing before and while the woman entered the office.
The progressive past aspect is most often used in sentences that express past actions that progressed in time in the past, that ended from an interruption including specific times, that occurred simultaneously, that describe the atmosphere, and that are repetitive and irritating. For example:
- The boys were playing football all day yesterday. (progressed in time)
- She was cooking dinner when the doorbell rang. (interruption)
- My puppy was barking while my cat was meowing. (simultaneous)
- When the teacher entered the classroom, all the students were studying. (atmosphere)
- The neighbors were always mowing the lawn early in the morning. (repetitive and irritating)
Past progressive sentences can contain only adverbials that express times in the past or immediate present such as yesterday, today, last week, and the other morning or that express past or simultaneous events. Past progressive sentences cannot contain adverbials that express times in the future. For example:
- Her toddler was talking all day yesterday. (correct)
- *Her toddler was talking all day tomorrow. (incorrect)
- The old woman was feeling ill last week. (correct)
- He was rollerblading when he fell down. (correct)
Notice that adverb clauses that begin with the subordinating conjunction while usually include past progressive verbs and adverb clauses that begin with the subordinating conjunction when usually include simple past verbs.