【C15】______A．whyB．whatC．whoseD．that

His brother had become a teacher, ______ he wanted to be.A．whoB．whatC．whichD．that

The fact ______ he does so in so short a period of time challenges explanation.A．whyB．that

I doubt_____he is the murderer because he is not on the scene at that moment.A．whyB．thatC．

Jack was soon told the fact______he did was not necessary.A．whyB．that whatC．howD．what

Mary wrote an article on _____.A、whyB、whatC、whoD、that

_________(63)A.which B.whatC.that D.those