使つかいこなす

godan verb (-su), transitive verb

master; handle skillfully; make full use of

Implies not just using something, but using it with full proficiency, having mastered its functions or nuances. Often used for tools, software, languages, or skills.

• 彼かれは新あたらしいソフトをすぐに使つかいこなせるようになった。

  He quickly became able to master the new software.

• この包ほう丁ちょうはプロの料りょう理り人にんでも使つかいこなすのが難むずかしい。

  Even professional chefs find it difficult to handle this knife skillfully.

• 英えい語ごを使つかいこなすには、たくさんの練れん習しゅうが必ひつ要ようだ。

  To acquire a command of English, a lot of practice is necessary.