高中英语表语从句单选题

______ surprised the hostess most is _______ one of her friends left the party without saying a word.

A．What, what

B．What, that

C．That, that

D．That, what

Great changes have taken place in that school. It is no longer ______ it was 20 years ago, _____ it was so poorly equipped.

A．what; when

B．that; which

C．what; which

D．which; that

_____ the flight to New York will be delayed is ____ I'm especially worried about.

A．If; what

B．Whether; that

C．When; that

D．Whether; what