单语范例（未经PONS编辑处理）
Carter became the first sitting president to testify under oath as part of an investigation of that president.
en.wikipedia.org He was suggesting, albeit coyly, that a sitting president is a traitor.
www.afr.com When brought to the station however, the officers became unsure if a sitting president could be formally charged if he had not been impeached.
en.wikipedia.org As special counsel, he became the first lawyer to question a sitting president under oath as part of an investigation of that president.
en.wikipedia.org It is the first time a sitting president has arrived on the deck of an aircraft carrier by plane.
en.wikipedia.org