Was it not until you began to work ___ how much time you had wasted?
A.did you realizeB.that you realizedC.did you not realizeD.that you didn’t realize在线课程B
解析：
考查特殊的强调句：it was not until..that…直到才，句意：直到你开始工作你才意识到浪费了多少时间吗？选B。