In Tobira chapter 11 grammar, one of the examples is 奈良は京都と並んで、古い歴史のある町で、日本の首都だったこともある。

I don't seem to find any information about たこともある on the entire web.

I understand there is no difference between (verb casual non past)+こともある/ことがある, which means sometimes or there are times when.

I was warned not to confuse with the construction (verb た-form)+ことがある, which means to have done something before. Is たことがある the same as た+こともある?

  • 1
    You almost get it. Just combine 日本の首都だった and 'there were times when'.
    – sundowner
    Feb 12, 2023 at 7:28

2 Answers 2


I think you should stick just to ことがある. (In this sense, yes たことがある is た+ことがある).

ことがある means did something before as you understand. More abstractly, it expresses a past experience.

  • 私はアメリカに行ったことがある I've been to the US.

Whether it translates to present perfect or past tense in English depends on the meaning.

  • 奈良は日本の首都だったことがある

can be translated Nara was once the capital of Japan. Here it in a sense express an 'experience' of the city Nara.

こともある could be Nara was also ..., but it should be clearer to say There was also a time when Nara was the capital of Japan.

  • 1
    I'm not an expert, but personally I read this as using the "extent" meaning of も, that is: "Nara was even (once) the capital of Japan"..
    – Foogod
    Feb 13, 2023 at 17:58
  • @Foogod You're right, but I don't think it's totally distinct.
    – sundowner
    Feb 13, 2023 at 22:29

Short answer: であることがある becomes だったことがある by adding た to the main verb.(†) It then comes だったこともある by replacing が with も to mean "additionally/also".

In this case も/が both work, and doesn't change the meaning of the sentence too much. You can replace が with も when mentioning one more thing. It can add emphasis, like "guess what, it was also..." but the emphasis is usually weak, if any (and that is why I say it doesn't change the meaning too much). If you start the paragraph by using Xも (which implies there is something similar to X in the immediate context), that would probably be strange, but that's not the case here.

If you want to more clearly emphasize the last part, you can say 日本の首都だったことさえある.

This is independent from the たことがある construction. The same distinction applies to its non-past form: することある ("sometimes I do X"), することある ("sometimes I also do X") and することさえある ("sometimes, I even do X"). Or any other cases like 花咲いてます / 花咲いてます / 花さえ咲いてます.

(†) Technically, there is one more step in between (である→であった→だった) but I think that's besides the point here.

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