题目内容：
Which of the following best represents the order from a harsh command to a very polite__________request??
Could you close the door?
Close the door.
Please close the door.
Would you please close the door?
A.b-c-a-d
B.c-b-a-d
C.d-a-c-b
D.c-b-d-a
参考答案：
答案解析：