1.I have no idea. 我不知道。

2.I have no clue.

3.It beats me. 你把我问到了。我被难倒了。我不知道。
A: Have you seen my notebook? I put it on the table hours ago.
B: Beats me.
A: 你又看到我的笔记本吗？我几个小时前把它放桌上了。
B：不知道。

4.Not as far as I know. 据我所知不。

5.“How should I know?” 我怎么知道？
A：Where did I leave my phone?
B：How should I know?
A：我把我手机放哪啦？
B：我怎么知道？

6.Don't ask me. 不要问我。

7.Search me. 我可不知道。

8.Dunno = don't know.
I dunno. 我不知道。