我不清楚/我不太清楚都是I don't know.
例句：
在杰克的名字旁边打个问号——他来不来我不清楚。
Put a query against Jack's name ─ I'm not sure if he's coming.
我不清楚他什么时候来。
I am uncertain when he will come.
他的孩子究竟多大我不清楚，反正不超过20岁。
I don't know just exactly how old his child is, but certainly not older than twenty.
我不太清楚下一步该怎么办。
I don't quite know what to do next.
电话里有回音，我听不清楚。
There was an echo on the line and I couldn't hear clearly.
