Are you going to attend the meeting _______ tomorrow?

Are you going to attend the meeting _______ tomorrow?
A.to be held B.being held　　 C.will be held　　　　 D.held
This is one of the questions _______ at the meeting now.
A.to discuss　　　　　　　　　 B.to be discussed
C.being discussed　　　　　　　D.discussed
一个选A一个选C 为什么?
第一题为什么不可以选B
第二题为什么不可以选B?