Proper use of ◎ことは◎ for する verbs


There is a grammar rule in DoBJG which looks like ◎ことは◎, where both ◎ are the
same verbs (or adjectives). But there is no examples with する-verbs in this
book.

Which one is correct?

  * 私は日本語を勉強することは勉強しましたが不合格でした。
  * 私は日本語を勉強することはしましたが不合格でした。

If none, how should I construct a sentence using said grammar?




Both are grammatical and perfectly make sense, but the former looks a bit too
wordy to me. Anyway, this is a rather literary construction, and probably
勉強するにはしたが or 勉強しはしたが is more common, according to some quick searches on
[BCCWJ](http://www.kotonoha.gr.jp/shonagon/).




Both are grammatical and perfectly make sense, but the former looks a bit too
wordy to me. Anyway, this is a rather literary construction, and probably
勉強するにはしたが or 勉強しはしたが is more common, according to some quick searches on
[BCCWJ](http://www.kotonoha.gr.jp/shonagon/).

