"while" with Past Simple and Past Continuous (with 2 examples)

Question

1. Could you explain, please, why "went" is only correct here (that says my grammar book)? Can't I use Past Continuious here, can I?

2. Why in the first example is used "... while I went to park..." (Past Simple) but in the second one - "... while Liam was filling in..." (Past Continuous)? Why that is so if both "go" and "fill in" are action verbs?

3. It is known that "while" has different meanings - DURING, ALTHOUGH, BUT. Can this fact impact on your choice between Past Simple & Past Continuous?

I left my parents at the teminal building with instructions to get in the queue at the check-in desk while I went to park my car in the long-term car park.

Meg went with Shaun to the photo machine while Liam was filling in the forms.

Answer 1

For both example sentences, I agree with your book that "went" is correct and "was going" is incorrect. But why?

First, past continuous events aren't the main idea of the sentence. Rather, they provide the context for events in the simple past.

Second, if a simple past event happens "while" a past continuous event is happening, it always means the simple past event only happens after the past continuous event has started.

In the first example sentence, with "was going", it would mean that you left your parents while you were going, as in, you left after you had already left. This is impossible.

In the second example sentence, if both clauses were in the past continuous, there would be no simple past story, so the sentence would be about nothing other than describing a scene, which might be the context for some other simple past clause. This sentence appears to be about what Meg did, so it should be in the simple past.