開か

In a sentence

• ドアが開かないように鍵を掛けました。

  I locked the door so it wouldn't open.

  Here, '開か' is used as a verb in its negative potential form implying the door cannot be opened.

• そのテーマについて自由に意見交換する場が開かれた。

  A place for freely exchanging opinions on that theme was opened.

  Here, '開か' is part of the verb '開かれる', meaning 'to be opened', suggesting a meeting or forum is being convened.

• 彼の考えはとても開かれたものでした。

  His thinking was very open-minded.

  Here, '開か' is part of the adjective '開かれた', which metaphorically means being open, as in open-minded or progressive.