_____________ the Games will be held in Beijing is not known. 

The employees consider their boss unfair and unreasonable because he is not _________ in dealing with company affairs.

We students should hunger_____ knowledge and_____ ourselves with knowledge for the competition nowadays is very fierce.

He didn’t make ______ clear when and where the meeting would be held.

 No one knows exactly when our ancestors started talking，but new evidence suggests  _______might have happened a long time ago．