关于倒装句的用法我还是弄不懂,请大家来教教我,谢谢

关于倒装句的用法我还是弄不懂,请大家来教教我,谢谢
we never saw him again,___hear from him.
A.we nor did B.we did nor C.nor we did D.nor did we
I don't know _____.
A.which room he lives B.which room does he live C.which room he lives in D.which room will he live in
(第一题用了倒装,为什么第二题不用倒装句?第一题句首“我没有再看见过他.”有否定的意思,第二题“我不知道...”也有否定的意思,为什么第二题没有用倒装句呢?
第一题选D,第二题选C