did the students realize that they were mistaken about spiders.
A. It was until then
B. It was not until then
C. Not until then
D. Not until when
网友回答
A. It was until then
B. It was not until then
(答案→)C. Not until then
D. Not until when
解析：考查倒装结构。Not 否定词，否定词放句首，句子要倒装。后面本来应该是 the students did realize that.....，现在变成了 did the students realize that倒装了。选C。