For example, consider the two following options:

  • 日本語の本が読めたい。
  • 日本語の本が読むことができるになりたい。

Is the first construction valid? If so, how is it different from the second (in terms of meaning, formality, etc.)?

1 Answer 1


Both sentences are ungrammatical. The correct forms are:

  • 日本語の本が読めるようになりたい。
  • 日本語の本読むことができるようになりたい。

You cannot directly combine the the potential-form and the tai-form. You cannot combine the dictionary-form and になる, either. The workaround for both cases is ようになる. The usage is explained in many other pages including this.

Also note that 本読むことができる is incorrect because 本が読むこと itself has no potential form. You have to say 本を読むことができる instead.

The difference between the two is fairly small, but please read: ことができる versus V~える form

  • I've come across the ことができる versus V~える link several times before and I always leave feeling unsatisfied. The top rated answer makes quite a distinction between the uses, but you and others seem to downplay that difference. I'd be interested to know to what extent you agree with the top rated answer? Commented Jan 7, 2020 at 15:35
  • 1
    @user3856370 Um...I admit I linked to that question without reading seriously, but I think ことができる can refer to allowance/permission, too. For example it's not wrong to say ここでBBQをすることができますか instead of ここでBBQをしてもいいですか. At least in the OP's case, the difference is subtle.
    – naruto
    Commented Jan 8, 2020 at 1:33
  • Is that really true? I can find a lot of citations from what appear to be Japanese native speakers that use the desirative directly linked to the potential form all the time. “読めたい” has so many citations on google as do similar constructions with many other verbs.
    – Zorf
    Commented Apr 10, 2023 at 7:21
  • Followup, after some thinking this feels like things such as “ありたい”, “綺麗でありたい” or “早くありたい”, people say that “なりたい” must be used, but Japanese people do use them. I don't think rule that the tai-form can't be combined with stative verbs or adjectives without use of “なる” in between is all that followed in practice.
    – Zorf
    Commented Apr 10, 2023 at 7:48
  • @Zorf Why did you suddenly bring up ありたい? Who said ありたい is wrong? It's a perfectly correct expression and contains no potential form in the first place. 綺麗でありたい and 綺麗になりたい have completely different meanings. 読めたい is highly broken to say the least (my IME refuses to convert よめたい into 読めたい), and it's safe to say it's wrong to a beginner.
    – naruto
    Commented Apr 10, 2023 at 8:56

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