"She became a serious ill."
(彼女は大病をした。)
解説
行為と結果を一つにした「する」の文例を英訳してみましょう。「失恋した」(She was disappointed in love.)、「赤ん坊が発熱した」(The baby became feverish.)、「試験で失敗した」(She was unsuccessful in the exam.)、「妊娠した」(She became pregnant.)、「大金を手にした」(She has come into a fortune.)、「成功した」(She was successful. / She has succeeded in her undertaking.)