请帮忙看一下这两个英语句子
Mr Johnson and his______son don't always understand each other.
A.older B.elder C.the oldest D.the eldest
What I would do is to go___________________.
A.really quietly somewhere
B.somewhere quietly really
C.really quiet somewhere
D.somewhere really quiet
其中第二句句子麻烦您说出语法的理由.