か

1. Origins, structure, and basic meaning

• Structure: Add か after a polite predicate to form a question.
• Basic usage: これはあなたの傘ですか。 checks whether the umbrella belongs to the listener.

2. Common pitfalls and similar expressions

• Preserving the predicate's meaning
  • 来ますか asks whether someone will come; 来られますか is used in contexts asking whether they can come. Adding か preserves the potential meaning in the verb.
• Questions with an interrogative
  • 何を食べますか asks what will be eaten and calls for specific information. Not every question with か is answered simply with yes or no.