If you're confused about the difference between "it's" and "its", or unsure how to spell "cemetery", you're not alone, and there's plenty of evidence to prove it.

That's the conclusion of two young Americans who took it upon themselves to correct public typos during a three-month road trip across the United States. They have written about the trip in a book that exposes deficits in both public education and attention to detail.

"The Great Typo Hunt" describes a nationwide mission by Jeff Deck and Benjamin Herson, both 30, to rid America of signs that add an extra "n" to "dining", or insist that "shipping" is spelled with one "p".

Deck, a magazine editor, and Herson, a bookseller, drove across the country in the spring of 2008 armed with sharpies, pens and white-out, correcting spelling, removing surplus apostrophes and untangling subject-verb disagreement on signs outside stores, gas stations, parks and public buildings.

Calling themselves the Typo Eradication Advancement League, they found hundreds of signs indicating the writers either didn't know or didn't care that their spelling, grammar, or punctuation was wrong, and were apparentlyunaware that their mistakes risked exposing them to public derision or, worse, misunderstanding.

In Atlanta, they found a sign advertising both a "pregnacy" test and a "souviner" of the city to remind tourists of their visit.

In Arizona, a placard urging tourists to bring their "camera's" prompted Deck and Herson to remove the gratuitous apostrophe, leaving the sign with a gap that was at least less offensive than what it replaced.

Sensitive to the charge of being overzealous pedants, they argue that public typos are about more than just a few misplaced punctuation marks. Such errors may lead the reader to get a poor impression of the writer in general, they argue.

"If you put a bunch of typos out for the world to see, people might draw conclusions about attention to detail in other matters," Deck said in an interview.

When they found public typos, Deck and Herson were careful to seek the permission of the signs' owners to make the needed changes.

Around 60 percent took a defensiveposture and declined any typo services, notably two people who threatened the pair when they were about to fix a sign on the Canadian side of Niagara Falls. They were warned to "keep walking or they would make sure we didn't walk again," Deck said.

• conclusion [kən´klu:ʒən] n.结束；结论；推论 (初中英语单词)
• mission [´miʃən] n.代表团；使馆vt.派遣 (初中英语单词)
• spelling [´speliŋ] n.拼法；缀字 (初中英语单词)
• league [li:g] n.同盟；社团 (初中英语单词)
• punctuation [,pʌŋktju´eiʃen] n.标点符号；标点法 (初中英语单词)
• advertising [´ædvətaiziŋ] n.广告a.广告的 (初中英语单词)
• remind [ri´maind] vt.提醒；使记(想)起 (初中英语单词)
• charge [tʃɑ:dʒ] v.收费；冲锋 n.费用 (初中英语单词)
• impression [im´preʃən] n.印刷；印象；效果 (初中英语单词)
• writer [´raitə] n.作者；作家 (初中英语单词)
• interview [´intəvju:] n.&vt.接见；会见；交谈 (初中英语单词)
• permission [pə´miʃən] n.允许；同意；许可 (初中英语单词)
• canadian [kə´neidiən] a.加拿大的n.加拿大人 (初中英语单词)
• surplus [´sə:pləs] n.&a.剩余(的) (高中英语单词)
• apparently [ə´pærəntli] ad.显然，表面上地 (高中英语单词)
• arizona [,æri´zəunə] n.亚利桑那(州) (高中英语单词)
• offensive [ə´fensiv] a.冒犯的 n.进攻 (高中英语单词)
• sensitive [´sensitiv] a.敏感的；感光的 (高中英语单词)
• advancement [əd´vɑ:nsmənt] n.前进；促进；提升 (英语四级单词)
• unaware [,ʌnə´weə] a.不知道的；不觉察的 (英语四级单词)
• atlanta [ət´læntə] n.亚特兰大 (英语四级单词)
• defensive [di´fensiv] a.&n.防御(的) (英语四级单词)
• niagara [nai´ægərə] n.尼亚加拉河 (英语四级单词)
• disagreement [,disə´gri:mənt] n.不一致；争论 (英语六级单词)
• calling [´kɔ:liŋ] n.点名；职业；欲望 (英语六级单词)
• derision [di´riʒən] n.嘲笑，嘲弄 (英语六级单词)
• misunderstanding [,misʌndə´stændiŋ] n.误解；隔阂 (英语六级单词)
• posture [´pɔstʃə] n.姿势 v.故作姿态 (英语六级单词)
• notably [´nəutəbli] ad.显著地；著名地 (英语六级单词)