各位大大,
想要请教一题文法,
This memo is written to inform you of the ___ in which employees may request
holiday time off.
(A) ordered (B) orders (C) order (D) ordering
正确答案是 (C) order.
想请问为什么不能选(B) orders啊?
谢谢!

因为顺序只有一个