It is not unmon for there problems of munication between the old and the young.
A. being
B. would be
C. be
D. to be
网友回答
A. being
B. would be
C. be
(答案→)D. to be
解析：考查句型：It is +adj for sb to do sth，it是形式主语，不定式是真正的主语，逻辑主语是there，动词用be，句意：在老人和年轻人之间有交流问题，很正常。选D。