http://play.inginf.units.it/#/level/1
\d+
http://play.inginf.units.it/#/level/2
(\w+)(\:\w+){5}
(\w+:){5}\w+
http://play.inginf.units.it/#/level/3
ftp://ftp\d?\d?\.?\w?\w?\.FreeBSD\.org/pub/FreeBSD/
ftp:\S+
http://play.inginf.units.it/#/level/4
\$.+?\$
http://play.inginf.units.it/#/level/5
\d+(\.\d+)+
(\d+\.){3}\d+
http://play.inginf.units.it/#/level/6
href=(['"]).+?\1
http://play.inginf.units.it/#/level/7
http://[\S]+(?:(?=\s|\.|\>)) (Not Working)
http://[^ >]+[\w/]
http://play.inginf.units.it/#/level/8
<h(\d)>?.+</h\1>
http://play.inginf.units.it/#/level/9
\(?\d{3}\)?.\d{3}.\d{4}
\(?\d+\)?[ -./]\d+[-.]\d+
http://play.inginf.units.it/#/level/10
\w+\,\s.+?\w+ (Not Working)
(?<=[{ ])\w+(-\w+)?,( [A-Z]\w*(({.+?}|')\w+)?)+
http://play.inginf.units.it/#/level/11
(?<=<h(\d)>).+?(?=</h\1>) (Not Working)
(?<=<h(\d).*?>).+(?=</h\1>)
http://play.inginf.units.it/#/level/12
(?<=\d+\.\s)\w+\,\s[\.\w]+(?=[\,\:])
(?<=\. )\w+, (.\.)+
I got a Solution for Level 10(Without Positive "Lookbefore"'s):
([A-Z]\w+-)?[A-Z]\w+(,\s)A-Z?('Ona)?(\sA-Z?)?
PS: because in Safari Lookbefores don't work