1. That is the place in which we can play.

2. That is the place on which we can play.

3. That is the place at which we can play.

4. That is the place where we can play.
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Which preposition do we have to use, at, on, or in? Are they all possible?

All those prepositions will work, depending on what the reference is: on a field, in a gymnasium, at the ballpark.

Sentence 4 is the best!

Sentence 4 is more suitable than others

In the given sentences, all four prepositions - "in," "on," "at," and "where" - are possible choices depending on the intended meaning.

1. "That is the place in which we can play."
The preposition "in" is used to indicate being inside or within an enclosed space. So, this sentence suggests that the place itself is an enclosed area where playing is possible.

2. "That is the place on which we can play."
The preposition "on" suggests that the place in question is a surface or platform upon which playing can happen. It implies that the playing activity occurs on top of or directly on the place mentioned.

3. "That is the place at which we can play."
The preposition "at" indicates a specific location or point. This sentence suggests that the place is precisely where the playing activity takes place.

4. "That is the place where we can play."
"Where" is a relative adverb that functions as an adverbial clause introducing a location. In this sentence, "where" introduces a subordinate clause that describes the location of the place where playing can happen.

To determine the most appropriate preposition, consider the context and the intended meaning. Each preposition implies a slightly different relationship between the place and the act of playing.