～ことがある

The grammar structure ～ことがある is used to express having the experience of doing something in the past or that there are times when a certain action or situation occurs.

• Expressing Experiences: When used with the past tense of a verb (V[た]), it indicates that the speaker has experienced or done something at least once.

  にっぽん日本にいった行ったことがあります。

  I have been to Japan.
  すし寿司をたべた食べたことがありますかきごう？

  Have you ever eaten sushi?

  To express never having done something, negate the verb:

  ぴあのピアノをひいた弾いたことがありません。

  I have never played the piano.

• Indicating Repeated or Occasional Situations: In some contexts, ～ことがある can also indicate that something occasionally happens or that there are times when it happens.

  かれ彼はがっこう学校をやすむ休むことがあります。

  He sometimes skips school.
  でんしゃ電車がおくれる遅れることがあります。

  There are times when the train is late.