答案选C
1.翻译为,我得知他要去美国了,但他什么时候走他自己决定
2.名词性从句(具体说这里是主语从句),句中应该是引导词+正常语序
When(引导词)he leaves(他离开)
3.再举例,I don't know where he is
What you should know is that ...
Do you understand what I means?
A不行,没有主语啊,也不能用动名词(或现在分词),when leaving不能算是动名词做主语,他说的是错的,我的英语很好的,请相信我