4.They are

4.They are ____ of different presses(出版社).Now they are having a meeting

题目应该是这样的.
4. They are ____ of different presses(出版社). Now they are having a meeting in one of the ____ office.
A. editor-in-chiefs, editors-in-chief's
B. editors-in-chief, editor-in-chief's
C. editors-in-chiefs, editor's-in-chief's
D. editors-in-chief, editors-in-chief's
选D第一空 editors-in-chief, 第二空editors-in-chief's
这个单词单数形式是editors-in-chief,第一空主语是they所以得用复数,复合词的复数要加在中心词的后面,所以是editors-in-chief.第二空是所有格,直接在后面加's就行