It is not uncommon for there___problems of communication between the old and the young.
A.being
B.would be
C.be
D.to be
我选B,答案D.请问语法上A,B为啥不成,为什么只能选D,谢谢

It is absolutely essential that William___his study in spite of some learning difficulties.
A.will continue
B.continued
C.continue
D.continues
我选D,正确C,请问这是什么语法现象啊,原因,谢谢
也许有误吧,我也郁闷哪,不知道,谢谢你,真的太感谢啦