我不知道他是个教师还是别的'什么。
I don't know if he's a teacher or what.
我不知道我一阵大哭持续了多久。
I don't know how long my crying jag lasted.
太好了。我不知道怎样才能报答你。
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样的噪音！
I don't know how you tolerate that noise!
我不知道。我没有参与那场争论。
I don't know. I wasn't in on that particular argument.