恳请各位大侠赐教：）
大家好，由于在下才疏学浅，所以在学习英语的时候遇到了很多困难，现在就又碰到了新的困难，恳请大家赐教，谢谢：）
问题1：I will never know what was on his mind at the time, nor will anyone
else. 请问大家，这句话是什么意思，我怎么绕不过来呢？
问题2：Jack is one of those men who I am sure always do ______best even in
the most difficult situations.
A his B your C their D one's
请问大家此题为什么选C 呢而不选A呢？
谢谢大家：）
