--How long are you staying ? -- I don’t know . .A. It depends.B. That’s OK.C. Never mind.

问题补充：

--How long are you staying ?

-- I don’t know . .

A. It depends.

B. That’s OK.

C. Never mind.

D. It doesn’t matter.

答案：

(答案→)A. It depends.

B. That’s OK.

C. Never mind.

D. It doesn’t matter.

解析：考查情景交际。“你要待多久？”“不知道。要看情况而定。”A“视情况而定”；B“好的”；C“没关系”；D“没关系”。故选A。