Not until then _____ their marriage was breaking up because they had little in common.

A．did I realize

B．I realized

C．had I realize

D．has I realized

给下列测量记录补上单位：一根火柴的长度约为40______；南京长江二桥全长21.97______；一位初二的学生脉搏跳动10次的时间约为0.2______．