Under no circumstances the difficulties when they were on an expedition to the Antarctic．
A. they gave way to
B. did they give way to
C. they had given way to
D. had they given way to
网友回答
A. they gave way to
(答案→)B. did they give way to
C. they had given way to
D. had they given way to
解析：考查倒装句。否定词放在句首，后面使用部分倒装，under no circumstances绝不，是一个否定词，放在句首，后面使用部分倒装。排除ＡＣ。部分倒装只需要把助动词提前即可，故B正确。