verb · to lay or establish (a foundation, basis, or groundwork)

通过努力，他为公司未来的发展打下了坚实的基础。

verb · to capture or seize (a city, territory, or position) through military force

在猛烈的进攻下，我军只用了三天就打下了这座边境小城。

verb · to bring down an aerial object (such as a bird or aircraft) by shooting

防空部队成功地打下了一架敌方的侦察机。