[Grammar] Past Perfect VS Past Perfect Continuous: had worked/had been working

[naweewra]

Hello,

Are these two sentences equally acceptable?

a) She had worked in that company for 20 years before she retired.

b) She had been working in that company for 20 years before she retired.

In the Present Tense, there doesn't seem to be a lot of difference.

c) She has worked in that company for 20 years.

d) She has been working in that company for 20 years.

But when it is in the past and there's another past action involved, I'm more inclined towards a) because the action was completed (Past Perfect) before another and that seems to be the distinction between the Past Perfect and the Past Perfect Continuous. Do I understand this correctly?

Does it make a difference if "before" is changed to "when"?

e) She had worked in that company for 20 years when she retired.

f) She had been working in that company for 20 years when she retired.

Thank you.

Nawee

 

[Raymott]

But when it is in the past and there's another past action involved, I'm more inclined towards a) because the action was completed (Past Perfect) before another and that seems to be the distinction between the Past Perfect and the Past Perfect Continuous. Do I understand this correctly?

No, not really. They are both past perfect tenses, and both acceptable.
The continuous sounds better to me if you use 'when'.