whilecrossingthemountainarea,allthemencarriedgunslesttheybywildanimals.A.shouldbeattackedB.wouldbeattacked这两个答案哪个对,为什么?不懂不懂~

Question

while crossing the mountain area,all the men carried guns lest they_____by wild animals.
A.should be attacked B.would be attacked
这两个答案哪个对,为什么?
不懂不懂~

Answer 1

If 从句 主句
与现在事实相反 动词的过去式(be 为were) Would (should)+动词原形
与过去事实相反 动词的过去完成式(had +动词的过去分词) Would (should,could,might) + have + 动词的过去分词
与将来事实相反 动词的过去式
（be 为were）
2.Were + 不定式
3.Should + 动词原形 Would (should,could,might) + 动词原形