"had talked" vs "were talking"

Question

Would you please explain the differences between these sentences?

1. We had talked when someone knocked at the door.

2. We were talking when someone knocked at the door.

Answer 1

Lets start with the first sentence:

We had talked when someone knocked at the door.

In general, the perfect aspect is used to talk about a finished event. In this sentence, the event is "talking". Also, we have this clause "when someone knocked at the door" which is called an adverbial clause. It acts as an adverb of time, providing more information about the finished event- "talking". Thus, this sentence means that:

Our talk was already finished when someone knocked the door.

As you can see, thanks to the perfect aspect, the chronological order of events is obvious. In other words, we can say: "After our talk finished, someone knocked the door."

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In the case of the second sentence, you can easily discern the past progressive structure. Progressive aspects are used to talk about events that are (or were) in progress. Let us check the second sentence:

We were talking when someone knocked at the door.

In this sentence "we were talking" refers to the process of talking. It implies an action which continued during a period of time. It does not convey an instance of something or a finished action. Again, we have the same adverbial clause. Thus, the second sentence means:

We were in the middle of talking when someone knocked the door.