----Why do you look so tired ?--I am writing a report for the newspaper.A. WhenBBeca

问题补充：

----Why do you look so tired ?

----I am writing a report for the newspaper.

A. When

BBecause

C. Until

D. Although

答案：

A. When

(答案→)B. Because

C. Until

D. Although

解析：根据题干，本句的意思是：---为什么你看上去这么累？---因为我正为报社写一篇报道。本句是解释累的原因。故用because。所以本题选B。