---on for years

Examples:

1.

I've entered pet photo contests off and on for years, always heartbroken and of course
shocked when my pets weren't chosen.

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2.

We spent $1,000 to get my sister out of jail. And this isn't the first time - this has been going
on for years.

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3.

In situations of conflict and natural disaster, family members often lose touch with each other
and wait a long time to hear news. Sometimes, the wait may go on for years.

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4.

Florida tobacco cases could go on for years, experts say.

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5.

The record company gave us some advance money, but it wasn't very much. Then they
gave us a small monthly allowance. That just went on for years.

(click here for original context)