This is the 1700th most frequent Japanese word.
かい
"かい" can mean "shell," "meeting," "floor," or act as a particle indicating effort or outcome, depending on context.
In this sentence, ’かい’ again acts as a question particle, inviting a response or opinion.
昨日の試合(しあい)はどうだったかい？
How was the match yesterday?
In this example, ’かい’ is used as an informal question particle, often found in conversational Japanese.
海(うみ)に行ったことはあるかい？
Have you ever been to the sea?
Here, ’かい’ serves as a casual question particle, maintaining the idea of seeking affirmation or information.