- Sit down please!.A. Hello.B. You sit down.C. Thank you!D. OK.

问题补充：

--- Sit down, please!

--- .

A. Hello.

B. You sit down.

C. Thank you!

D. OK.

答案：

A. Hello.

B. You sit down.

(答案→)C. Thank you!

D. OK.

解析：在英文中当别人请你坐下，你处于礼貌应该表示感谢，故选C。