A:looking, being built
B:looked, being built
C:being looked, building
D:looking, built
《史记》和《资治通鉴》是我国古代两部著名的史学著作。下列示意图中,哪一字母所代表时期的史实在这两部书中都能查阅到( )
《九章算术》的特点是( )