美国宪法中规定的总统誓词如下：
i do solemnly swear (or affirm) that i will faithfully execute the office of president of the united states, and will to the best of my ability, preserve, protect, and defend the constitution of the united states.
“我谨庄严宣誓，我必忠实执行合众国总统职务，竭尽全力，恪守、维护和捍卫合众国宪法。”
副总统宣誓誓词是：
i, a— b—, do solemnly swear (or affirm) that i will support and defend the constitution of the united states against all enemies, foreign and domestic; that i will bear true faith and allegiance to the same; that i take this obligation freely, without any mental reservation or purpose of evasion; and that i will well and faithfully discharge the duties of the office on which i am about to enter. so help me god.
“我谨庄严宣誓，我决心维护和捍卫合众国宪法，防止被国内外一切敌人侵犯。我将忠于宪法，恪守不渝。我自愿承担这项义务，毫无保留之意，也决无推诿之心。我必忠勤尽责，为执行我即将承担的职务鞠躬尽瘁。愿上帝助我。”
美国宪法使用的宣誓，用的动词时swear或affirm。
if you swear to do something,you promise in a serious way that you will do it.
if you affirm that something is true or that something exists, you state and publicly that is true or exist.
从解释也可以看出，swear侧重于发誓，宣誓的意思，而affirm侧重表示确认，证实之类的意思。
表示誓言方面，比较正式的誓言可以用oath。oath是那种很正式的，特别是对国家对人民的誓言。像美国总统这种宣誓的誓词，就是oath