Me as soon as possible easy question are the two most commonly used notations to denote the dates of historical events. however, most ancient civilizations did not use this method of marking dates. the christian calendar was introduced in rome only when the converted to christianity. this system of dating is still used internationally. using a dating system makes it easier to mark and compare historical events. are the two most commonly used notations to denote the dates of historical events. however, most ancient civilizations did not use this method of marking dates. the christian calendar was introduced in rome only when the converted to christianity. this system of dating is still used internationally. using a dating system makes it easier to mark and compare historical events. answer choices for the first blank bc and ad , ac and dc or century and era answer choices for the second blank egyptian emporors, greek emperors or roman emperors answers for the last blank uniform, modern, or historic