Construction "they had been running..."?

[Natalika]

They ......... for 3 hours when the storm suddenly broke.

(a) had been running
(b) have been running
(c) are running
(d) will be running
Why the right answer is (a) ? There is no word "before the storm" ..so they can keep on running.
I would write "have been running"..
Thank you.
Lika.

[Torsten]

Hi Lika,

Welcome to english-test.net and thanks for posting your questions. The key word here is 'broke' which is the simple past of 'break' This means we are talking about two actions that happened as a sequence: First they ran for 3 hours and then the storm broke so you need "had been running" to describe the first action.

Let me know what you think.
Thanks,
Torsten
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Test Of English for International Communication
TOEIC Preparation & TOEIC Vocabulary

[Natalika]

Hi, Torsten
Thank you for quick answer.
But if they keep on running?
They were running for 3 hours when the storm broke.
Is it correct ?
Thank you.
Lika

[Alan]

Hi,

I think the crucial point is that the length of time is mentioned. If it was omitted, then you could say: They were running when the storm broke. But the indication is that the storm broke after they had been running for 3 hours.

Alan
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English as a Second Language
You can read my ESL story 'the' vs. 'a/an'