David Holmes, a staffer from the U.S. Embassy in Ukraine, testifies before the U.S. House Intelligence Committee on Capitol Hill in Washington D.C., the United States, on Nov. 21, 2019. The last two witnesses scheduled for publicly testifying before a House panel as part of an impeachment inquiry into U.S. President Donald Trump offered their narratives of events relating to the investigation on Thursday. (Xinhua/Liu Jie)