the Forbidden City is almost 600 years old it is still very beautiful.A. Although; butB

问题补充：

the Forbidden City is almost 600 years old, it is still very beautiful.

A. Although; but

B. /; although

C. Although; /

D. Because; so

答案：

A. Although; but

B. /; although

(答案→)C. Although; /

D. Because; so

解析：although与but 不能同时使用，because与so 不能同时使用，再根据题意，选C