这个实际例子是最典型的例子

他入籍前没有被逮捕过，但N－４００表上还有一个
问题Have you ever commited a crime or offense for which you wer NOT arreated：他回答NO。但入籍后为了把他驱逐出境，非要说人家以前打过老婆，所以他在N－４００表回答那个
问题就是FRAUD了。在扯一点，他另一个问题(have you ever lied to an immigration officer?)也成为撒谎了

http://www.ice.gov/pi/news/newsreleases/articles/070313elpaso.htm?searchstring=denaturalize

On Thursday, U.S. District Judge Kathleen Cardone judicially denaturalized the 44-year-old Mexican native, and sentenced him to time served. ICE special agents arrested him in April 2006. Castro-Vasquez became a permanent resident in 1993, and a naturalized U.S. citizen in 2003. He is now pending deportation proceedings.

Castro was convicted of lying twice on his naturalization application. He answered "no" when asked if he had ever knowingly committed any crime for which he had not been arrested, when in fact he was known to assault his wife. He also lied when he answered "no" to never having given false testimony for the purpose of obtaining any immigration benefit.