Could I speak to ____________ is in charge of the company?

. She learnt both business and history, but she knows________of them well, though she can speak on subjects in general.

Nelson Mandela devoted all his life to the struggle of the African people and      of every nation that seeks freedom．

29. I have been absent for nearly half a month. I can't afford ________ week.

As we were asleep, ＿＿ of us heard the sound .