for certain

肯定地, 确凿地, 无疑地

例句与用法：

I don't yet know for certain.

我知道得不确切。

I couldn't say for certain when he'll arrive.

我说不准他什麽时候到。

For certain reasons I will be unable to attend the meeting.

因为某种原因，我不能出席这次会议。

I can't say for certain.

我说不准。

I don't know for certain.

我确实不知道。

I can't say for certain what to do.

我说不准该做什么。

I can't say for certain when he will arrive.

我说不准他什么时候会来。

详细释义：

肯定地

I don't know for certain.

我无法肯定。