问题补充：
Not until I began to work how much time I had wasted.
A. didn’t realize
B. did I realize
C. I didn’t realize
D. I realized
答案：
A. didn’t realize
(答案→)B. did I realize
C. I didn’t realize
D. I realized
解析：此题考查的是否定词放在句首，使用部分倒装，助动词往前提。not until放在句首从句不倒装，主句倒装，然后根据时态选B
