问题补充:
Not until he met with the difficulty the importance of group work.
A. he realized
B. did he realize
C. realized he
D. he didn’t realize
答案:
A. he realized
(答案→)B. did he realize
C. realized he
D. he didn’t realize
解析:考查倒装结构。句中否定词Not until放在句首,主句的主谓要用倒装结构,故选B。