Dave's ESL Cafe's Student Discussion Forums

[learner12]

Hello, teachers!!

The cost of living has greatly risen in the past thirty years.
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May I use "for the past thirty years" instead of "in the past thirty years"?

Do you have any differences between "for the past thirty years" and "in the past thirty years" when you use them?

Thank you in advance.

[pugachevV]

in as it is used here, expresses a period of time during which an event happens or a situation remains the case.

For, used in place of in expresses a length of time.

If you use "in" (which I prefer for this example) it means that the cost of living has increased greatly over the 30 years taken as a whole. It may have increased slightly in some years and a lot in other years, but on the whole it has increased greatly over the 30 year period in question.

If you say it has risen greatly for the past 30 years, it means that in every one of the years in question the cost of living has risen greatly.
As you can see, the difference is slight.

[learner12]

Dear pugachevV:

Thank you so much for your logical explanations.

I understood what you wrote.

Take care and have a nice day.