1. Which sports club are you in?

2. I am in the ping-pong club.

3. Which sports club are you on?
4. I am on the ping-pong club.
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Which expressions are correct? In this case, do we have to use 'in' or 'on'? Are both prepositions OK?

My answers: 1 and 2 are correct. In that case, use 'in'. No, both prepositions are not OK.

Only 1 and 2 are correct.

You can be on a team, but you're in a club. (I have no idea why!)

Both prepositions, "in" and "on," can be used to talk about sports clubs, but they convey slightly different meanings.

1. "Which sports club are you in?"
This expression suggests that you are a member of the sports club. It implies active participation and being part of the club as a member.

2. "I am in the ping-pong club."
This statement is correct and means that you are a member of the ping-pong club.

3. "Which sports club are you on?"
This expression suggests that you are a part of a team or roster within the sports club. It is commonly used in team sports to refer to being on a specific team within the club.

4. "I am on the ping-pong club."
Although this statement is commonly used, it is technically incorrect. Instead, you should say "I am on the ping-pong team" or "I am on the ping-pong roster" to convey that you are part of a specific group within the club.

In summary, both "in" and "on" can be used, but "in" is more commonly used to refer to being a member of a sports club, while "on" is usually used to refer to being part of a team within the club.