for all I know
1．to my knowledge就我所知
He may be in Africa for all I know．就我所知，他可能在非洲。
For all I know， he may have already left for school．就我所知，他可能已经上学去了。
2．（used like a negative） indicating that the speaker does not know at all（表示否定）不知道；不在乎
For all I know， you might be in Boston．我不知道你们会在波士顿。