我不知道他是個教師還是別的什么。
I don't know if he's a teacher or what.
我不知道我一陣大哭持續了多久。
I don't know how long my crying jag lasted.
太好了。我不知道怎樣才能報答你。
It was very kind. I don't know how I can ever repay you.
我不知道你怎么能忍受那樣的噪音！
I don't know how you tolerate that noise!
我不知道。我沒有參與那場爭論。
I don't know. I wasn't in on that particular argument.