题干
He realized his mistakes and took action to reduce the loss _________ it was too late.
A：until
B：when
C：before
D：as
答案(点此获取答案解析）
C
He realized his mistakes and took action to reduce the loss _________ it was too late.
A：until
B：when
C：before
D：as
，并将解集在数轴上表示出来．