What does in the hour mean?

[Sunshiney]

English Language Proficiency Tests, Advanced Level

ESL/EFL Test #649 "Prepositional Phrases - In, On, Out and Under (22)", question 3

I am so sick of living next to a train. It goes by my house every hour, ......... the hour, from 2 AM until 6 AM. It wakes me up every night.

(a) in
(b) on
(c) out
(d) under

English Language Proficiency Tests, Advanced Level

ESL/EFL Test #649 "Prepositional Phrases - In, On, Out and Under (22)", answer 3

I am so sick of living next to a train. It goes by my house every hour, on the hour, from 2 AM until 6 AM. It wakes me up every night.

Correct answer: (b) on
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What does in the hour mean ? Thx in advance

Sunshiney

[Alan]

Hi,

If you said 'in the hour', that would mean within the duration of one hour as in: He'll be back from work in the hour - he'll be back before an hour has passed.

Alan
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