He is the 3rd person to arrive at the party.

He will 3rd in the race.

He 3rds the race.

She is in the 3rd grade.

The 3rd grades are going on a field trip next week.

He is the 3rd person in line.

I always feel like a 3rd wheel when I hang out with my best friend and her boyfriend.

They always feel like 3rd wheels when they hang out with their couple friends.

The 3rd grader won the spelling bee competition.

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