かQuestion marking particle

か is the standard question particle, used at the end of sentences to form questions (e.g., どんな本が好きですか？ = 'What kind of books do you like?'). It also appears in the middle of other grammar patterns. かい is a casual, informal question particle often used by older men at the end of yes/no questions (e.g., 元気かい？ = 'Are you feeling okay?').

よ is a common sentence-ending particle used for emphasis, often indicating that the speaker is providing new information (e.g., 面白いですよ = 'It's interesting, I'm telling you!'). In contrast, か is the standard question particle, which has the opposite function, asking for information (e.g., 面白いですか？ = 'Is it interesting?').

か is the standard question particle, used at the end of sentences to ask questions (e.g., どんな本が好きですか？ = 'What kind of books do you like?') and also within other grammar patterns. っけ, on the other hand, is a casual sentence-ending particle used when trying to recall something (e.g., 名前はなんだっけ？ = 'What was his name again?').